Co-Op Mode (BTD6)/Strategies

Here are a list of strategies for the Co-Op Mode in BTD6.

Tips

 * Since cash is evenly distributed between players, you'll earn cash slowly, so Benjamin is a recommended hero and it is recommended to use Banana Farms.
 * Avoid using Captain Churchill or Adora unless your teammates are capable of farming money for you, as both will level very slowly once other players place other heroes and are very expensive to place.
 * It is actually easier to play with 1 teammate than with 2 or 3 teammates, as you gain more cash with less teammates and can thus build towers more easily.
 * Try to take advantage of what section you can place towers in. If you are restricted to the end of the map, use the land to place Spike Factories or Farms. If you are near the start, focus on the bulk of the defense and build towers to pop bloons.
 * Do not primarily focus on farming on early game. This can easily lead to losing on early rounds due to lack of bloon or MOAB popping power. A notorious tactic often seen in Quick Matches are players getting Benjamin and then only buying Monkey Banks.
 * Teammate badges on the teammate screen before starting a co-op game may or may not determine the skill of that player. A player who has 6 Easy badges might be more skilled than a player who has 1 Hard badge and vise versa. It is best to not rely on a single teammate to carry on co-op.
 * Rounds 40 and 63 are the most infamous rounds on a Co-Op game, and will be the rounds that most players will lose on, especially when playing on Quick Match.
 * To combat round 40, you should attempt to farm up defense to pop a M.O.A.B. and buy at least one MOAB Mauler. Relying on Benjamin's trojan isn't recommended unless your teammates still haven't placed their heroes.
 * Round 63 can be beaten by buying two Blade Maelstroms and timing the abilities correctly.
 * Other important rounds includes rounds 51 and 59, which have highly dangerous camo ceramics or leads that will end the game without sufficient camo defense.
 * Do not spam cash requests or spam money sends unless it is absolutely needed. It is annoying and only increases your chances that your teammates will mute you. Additionally, it takes off more time off the main defense for the team to put up with your antics.
 * You can use emotes properly to warn teammates to improve their defense, as it is easy to forget about camo, lead, or MOAB defense.
 * Playing with teammates on different platforms seems to have an impact on lag and disconnections. Whenever possible, try to match with teammates on the same platform (i.e. playing with teammates on mobile if you're playing on mobile).
 * Playing private matches can be better than playing Quick Matches, as most players you invite to a private match will be more skilled than players on Quick Matches.
 * You can also treat this mode like Half Cash and attempt the same strategies here.

Description of each hero's usefulness in Co-Op Mode

 * Quincy: Quincy is an all-around hero that is common in Quick Matches, and is surprisingly useful in co-op. Having a fast XP leveling curve, Quincy can quickly rack up his powerful levels such as level 7 and level 10 quickly. He has the ability to pop both camo and even leads at levels 5 and 7, respectively, allowing him to pop any type of bloon except D.D.T.s, although most co-op games don't go past round 80. Rapid Shot serves as a great damage per second fodder for M.O.A.B.s (especially on round 40), and Storm of Arrows can put short work on dense bloon rushes such as one ceramic wave on round 63 and the ceramic waves on rounds 76 and 78.
 * Gwendolin: Gwendolin is a common hero in Quick Matches and can see use as a decent bloon popping power, complete with a decent XP leveling curve. Her Cocktail of Fire and Firestorm abilities are capable of popping dense groups of bloons such as rounds 63, 76, and 78, and she can put short work on grouped bloons. Despite her advantages, she struggles more to MOABs than other heroes like Quincy or Benjamin.
 * Striker Jones: Striker Jones is rarely used in Quick Matches, as Striker Jones only sees niche in Bomb Shooter and Mortar Monkey defenses. His Concussive Shell can be a decent way to stun even M.O.A.B.s, but he lacks damage per second on his own and thus often suffers against combatting MOABs on his own. He is also unable to detect camo on his own. However, he best sees use in MOAB Mauler defense spam due to being able to grant Black Bloon and Zebra Bloon popping power to explosives, although such strategy is often unreliable in a public game as it is not easy to communicate that one will use Mauler spamming strategies.
 * Obyn Greenfoot: Obyn can be used as a good way to combat the early game, however he lacks MOAB popping power. He is best used for supporting early game at a cheap cost or for supporting magic towers on the Magic Monkeys Only game mode. Brambles can be used to counter early camo bloons, but often falls off once round 42 hits.
 * Captain Churchill: Even though Captain Churchill might seem like a versatile hero, he is not an ideal choice for this game mode unless you're playing on Deflation Mode. He has a slow XP leveling curve and a high cost, meaning it will likely be late when the player purchases him. In addition, due to his leveling curve, he will slow leveling XP of other heroes including himself and end up often not reaching level 10 before the end of the game mode. If Churchill has to be used, it is recommended to either buy a Hero Booster for him or buff him with a Berserker Brew Alchemist. Despite these shortcomings, he has decent grouped, camo, and MOAB popping power and often times can put short work on the round 40 M.O.A.B. alongside the midgame, although he needs support for rounds such as 63, 76, and 78.
 * Benjamin: Being a very common hero in Quick Match, Benjamin is highly recommended on this game mode unless you're playing on Deflation Mode or C.H.I.M.P.S., as Benjamin counters the reduced cash per pop by gaining additional money for the player. His Skimming ability affects all players and gives them additional cash per bloon spawn. His most notable use is for the Bloon Trojan and Syphon Funding, as the earlier can nullify the M.O.A.B.s during round 40 and the midgame, alongside reducing the threat of rushes such as rounds 63, 64, 75, 76, and 78. Biohack can be a small buff for towers, but be aware that this affects your teammates' towers and can backfire as a result. Despite these, do not rely on Bloon Trojan to beat round 40, as if there are other heroes placed, he will not be able to obtain Bloon Trojan before round 40 due to reduced XP given to him.
 * Ezili: Ezili is rarely used in Quick Matches, and is highly not recommended to use on Co-Op. Despite being able to easily defeat MOABs on late game, she has a slow XP leveling curve and has very minimal bloon damage on her own. Despite being able to pop camo by default, she is mostly incapable of popping M.O.A.B.s and ceramics on her own, lacks grouped damage, and does almost no damage to the MOAB on round 40, let alone the ceramics inside the MOAB. By the time the player does get the MOAB Hex, it wouldn't be very useful due to rounds before round 80 having very minimal amount of MOABs all in one round, and most co-op games often don't go past round 80. Her level 3 ability is not very useful as it can only be used on rounds with regrow and is functionally useless past round 80. Should Ezili be used in a co-op game, buy a Hero Booster as she doesn't do much without MOAB Hex, and boosting her via Berserker Brew has nearly no advantage on her downsides.
 * Pat Fusty: Even though Pat Fusty is rarely used in Quick Matches, he can be a very useful support hero in the long run. He has decent damage against grouped bloons on his own and his level 5 knockback can be capable of looping back MOABs and can be a cheap counter for round 40. His Rallying Roar ability can buff all of the towers close to him, making it very useful to combine with low damage but fast firing towers such as The Tack Zone and Sun Avatar. His main downside is his low leveling curve and lack of camo detection, although he should be treated as a support tower and shouldn't be relied on to beat most of the co-op match.
 * Adora: Although Adora is a common hero used in Quick Matches, she is highly not recommended to use on Co-Op. Despite having decent grouped damage, she lacks MOAB and ceramic popping power on her own and is unable to detect camo, and much like Ezili, does nearly no damage to the MOAB on round 40. Not helping is her slow XP leveling curve, which greatly suffers not only her leveling but the leveling of other heroes placed, and unlike Captain Churchill, who levels and level 10 ability greatly boosts him, Adora's levels does not boost her much and Ball of Light does not last long enough to deal with grouped rushes such as rounds 63, 64, 75, 76, and 78. Blood Sacrifice can only work on the towers the player owns, and is even more costly, meaning leveling up Adora is often not worth the cost of sacrificing. Should Adora be used in a co-op game, buy a Hero Booster as she doesn't do much without Ball of Light. Boosting her via Berserker Brew benefits her many projectiles quite well, but she levels too slowly to reach at a suitable synergy level with Alch buffs.
 * Admiral Brickell: Admiral Brickell is rarely used in Quick Matches due to her niche of Monkey Subs and Monkey Buccaneers, and isn't an ideal hero to use on Co-Op. It is imperative that you do not use her on maps without water, otherwise it will be the equivalent of having no hero without using a Portable Lake. Even then, Admiral Brickell requires the use of Subs and Buccaneers near her to support them via the level 3 ability. On her own, she lacks grouped popping power and MOAB popping power until Mega Mine, despite being able to pop lead (albeit unreliably) and camo, and also has a relatively slow XP levelling curve. With Subs and Buccaneers, she can excel as a decent support tower that can benefit aquatic towers in the long run, which can help on maps that is mostly composed of water.
 * Etienne: Etienne might seem like a hero with poor bloon popping power at first, but much like Quincy, he can end up being very powerful in the long run. With Drone Swarm, it provides decent damage per second against MOABs and can be used to defeat the round 40 MOAB rather easily. UAV can give camo detection to all towers and thus counters rounds such as 42, 51, 59, and 78. His fast XP levelling curve allows him to reap higher levels, and his UCAV ability is vastly useful for all bloon types, countering rounds 63, 64, 75, 76, and 78 with ease.
 * Sauda: Being an all-around hero despite limited range, Sauda proves to be a good choice for maps with decent curves, but overall she performs well on maps below Advanced Difficulty. She has a lot of popping power and damage for early rounds and her abilities can put up good work against tough early game rounds, especially rounds 40, 63, 76, and 78. However, she has a rather slow leveling curve and often will struggle against MOABs without abilities.
 * Psi: Psi is highly not recommended to use on Co-Op. Psi has a slow leveling curve for what little advantages Psi will gain. Psi usually doesn't ramp up in usefulness until level 14, when Psi can pop MOABs. As a result, Psi will not even damage most MOAB-class bloons (especially the round 40 MOAB and even the round 60 BFB and round 80 ZOMG). Alongside, Psi has extremely slow attack speed with not much pierce, making them suffer more against regular bloon rushes. Getting up to higher levels to enable Psi's ability to pop all types of bloons is usually nigh impossible due to the limited income on co-op. Psi's abilities might be able to come into use, but Psi levels too slowly to reach suitability to obtain such abilities. Should Psi be used in a co-op game, buy a Hero Booster as Psi doesn't do much without Psionic Scream, and boosting Psi via Berserker Brew has nearly no advantage on Psi's downsides.

Emote Interpretation
Emotes and Pre-Determined Messages are important for conveying messages to other players. Since a majority of players on Co-Op won't use external third-party social media apps such as Discord, the majority of all communication is primarily done via emotes. Outside of simply interpreting what other players may be thinking based on their cash amounts and certain upgrade choices, use of emotes and pre-determined messages are the only way to figure out what other players need or want.

Below are some common interpretations for all of the different default emotes. These interpretations may not always be fully correct, but do consider these interpretations as you play the game. Quotes have been added to display potential interpretations that players may be intending to speak out.

Since Trophy Store emotes are not available for all players, most of the listed emotes will use the default emotes.

"Hi!"

 * Speaking Player recognized another person
 * "I recognize you from somewhere."
 * Speaking Player wants to grab attention for another player, usually an idle Player Y
 * "Hello? Are you still here?"

"Ready!"

 * Speaking Player is ready to begin a game, as all their defensive setups are ready
 * "My defenses are ready. We should start the game soon"
 * "I'm ready to begin starting the game."
 * Speaking Player is ready to start a round where auto-start is off.
 * "I'm ready to begin the round."

"Well done"

 * Congratulating the team for good defense unironically
 * "Nice, we just beaten the Round 40 MOAB well. Now we should be safe for the next few rounds."

"Good job"

 * Gratitude for a player who had done a clutch save or did something worthy of congratulating
 * "Nice job defending."

"Thanks"

 * Thanking another player for providing sufficient donations
 * "Thank you for giving me enough money to buy Upgrade X / Hero X / Tower X that I wanted to afford."
 * Thanking another player for supporting them
 * "Thanks, it feels good to be appreciated by you."

"Sorry!"

 * Speaking Player announced they made a blunder
 * "I'm sorry for making a mistake I did."
 * Speaking Player stated that they themselves don't want to continue going past Freeplay or past Round 100 towards epic late-game, so they tell the others that the player who communicated the message may be leaving the game soon
 * "Sorry, can't play further."

"Slow!"

 * Speaking Player requests turning off Fast Forward, often to allow themselves to think while the game runs
 * "Please turn off Fast Forward. I need time to place something down carefully."

"AFK" (away from keyboard)

 * Speaking Player is likely going to be idle
 * "I will be away from the screen for a while, don't expect me to respond."

"GG" (good game)

 * Used when the game is approaching an end, whether it be a win or a loss, usually the first option
 * "Haha, looks like we're gonna win, so it's gonna be an easy win soon."
 * "Oh dear, I guess it's game over..."

Laughing Monkey head

 * Something considered funny by the Speaking Player
 * "Hehehe, that's a weird upgrade choice you got there."

Monkey head giving a thumbs up

 * Thanking another player for doing something Speaking Player intends to do and is favorable to them
 * "Thank you for giving me enough money to buy Upgrade X / Hero X / Tower X that I wanted to afford."
 * "Nice, we should be all sorted for the next few rounds after beating that difficult Round 40 MOAB flawlessly."
 * Appreciation for another player's choice of defense or a useful tower use that they consider helpful
 * "That's a pretty cool defense you've set up."
 * "Ooh nice, I like how you used an A-B-C Tower X to do Y"

A Monkey head giving a thumbs down

 * Unhappy about another player's possible blunder
 * "NO! Don't buy that upgrade."
 * "NO! You shouldn't have done that."

A dizzy Monkey head, resembling the one shown on the Defeat screen

 * Disconnection issues are making the game lag
 * "Oh dear, the lag is getting really tedious..."
 * There is a fatal blunder that has caused the defense to fail
 * "Uh oh, your income greed might've costed the game..."

A crying Monkey head

 * Speaking Player isn't happy with other players not going to their defense intentions
 * "Aww man... I wanted to get Upgrade X but you're not listening!"
 * "Aww man... I wanted to place down Hero X but you're not listening!"
 * "Aww man... I wanted the other player to get Upgrade X / Hero X but you're not listening!"
 * Speaking Player is fearing the next difficult rounds because of something they feel regretful about
 * "Oh no... not Round 40! We're dead!"
 * Speaking Player is saddened by needing to use a Continue or a Power to salvage the current game.
 * "Aww man... I had to use a Continue or Power, and now I used up some of my Monkey Money!"

Camo Green

 * Alerting Camo rounds
 * "Round 24 is coming, have your camo detection ready!"
 * Player wants a camo upgrade
 * "Please give me money so that I can buy Camo Upgrade X"
 * Additional camo countermeasures are required
 * "More camo detection is needed!"
 * "I need someone to provide decamo or give the defense with a Radar Scanner."

Lead Bloon

 * Alerting Lead rounds
 * Player wants lead popping power
 * "Please support me with extra lead defense"
 * If the player has a 0-0-0 Sniper, they may be trying to get a 1-0-0 Full Metal Jacket Sniper.
 * Likewise can be applied with a 0-0-0 Wizard, where 0-1-0 Fireball Wizard is wanted.

Zebra, Rainbow, and Ceramic

 * Alerting dense bloon rounds
 * Most often used as an alert of Round 63.
 * "Get ready for Round 63!"

MOAB, BFB, ZOMG, and BAD

 * Alerting MOAB-class bloons rounds
 * Mostly used as an alert of Round 40, the round where the first MOAB spawns
 * "Please give me defense for beating Round 40."
 * "Get your defenses ready for Round 40!"

Fire Cocktail, Concussive Shell, and Brambles

 * Alerts need of ability usage
 * "Use your abilities!"

Piggy Bank

 * Asking for money
 * "Please donate some money to me"
 * Subject Player wants to save up for a Monkey Bank or wants another player to get a Monkey Bank
 * "I want to buy a Bank"
 * "Please buy the Monkey Bank upgrade"
 * Requesting another player to empty their Banks
 * "Please empty your Banks"
 * Requesting other players to save money
 * "Please save your money"

Jungle's Bounty, Merchantman money bag, Support Chinook Crate

 * Requesting income production
 * "I would like to save up for money generation methods"
 * "Please buy income-generation upgrades"
 * "I would like to buy my first Banana Farm"
 * Requesting that other players should start farming
 * "Please start farming money."
 * Asking for money
 * "Please donate some money to me"

Hero Icons

 * Requesting another player to save up for a specific hero
 * "I would like you to buy Hero X"
 * "Please can someone place down Hero X?"
 * Requesting other players to donate money to afford specific hero
 * "I would like to save up for hero X"