Crosspathing/Dart Monkey

In Bloons TD 6, it is important to choose the best crosspathing for a specific tower in order to receive the best benefits out of that tower type. Towers have special roles to play for each stage of the game. The Dart Monkey in its core is a source of cheap early-game damage or fulfill a special niche with its higher upgrades.

Introduction
The Dart Monkey is mostly centered around being cheap options for popping bloons. For its later upgrades, each upgrade fulfills a different niche in the game depending on the respective upgrades' underlying roles.

In general, each path of the Dart Monkey is built specifically around optimizing one specific aspect. Path 1 is about pierce. Path 2 is about DPS. Path 3 is about range.

Tier 2 and below



 * 0-0-0: The most basic option for the Dart Monkey. Multiple of these are useful on early-game CHIMPS and are usually more efficient than upgrading existing Dart Monkeys.
 * 1-0-0: What you should do with this depends; If you're on CHIMPS or don't have the extra dart pops Knowledge, this is a good path. If otherwise, don't use it. Also don't use it with crossbow master, but do use it with sharp shooter. It's situational, but good.
 * 0-1-0: This is almost always good, as it just increases Attack speed, and no more. If not using it for Attack speed, just use it as a stepping stone for 0-2-0, a stepping stone for 0-3-0.
 * 0-0-1: In rare cases where range may be necessary, this upgrade can be helpful in itself. Otherwise it's just a stepping stone for 0-0-2.
 * 1-1-0: See 2-2-0
 * 1-0-1: Usually a stepping stone for 2-0-2
 * 0-1-1: Usually a stepping stone for 0-2-2
 * 2-0-0: Unlike 1-0-0, this is almost always good as it, along with 1-0-0, heavily increases pierce, especially with extra dart pops.
 * 0-2-0: It is mainly bought to use as stepping stone for 0-3-0.
 * 0-0-2: Useful as a cheap counter for Round 3 or as cheap camo range for Advanced Intel.
 * 2-1-0: See 2-2-0
 * 2-2-0: Useful if camo bloon detection isn't necessary.
 * 1-2-0: See 2-2-0
 * 0-2-1: Usually a stepping stone for 0-2-2
 * 1-0-2: 2-0-2, but cheaper and weaker. See 2-0-2
 * 2-0-2: This is basically, without knowledge, a slower firing, but cheaper, version of 2-0-0 Ninja.
 * 0-1-2: Usually a stepping stone for 0-2-2
 * 0-2-2: Usually a stepping stone for 0-2-3.

Spike-O-Pult

 * 3-0-0: If needing the large pierce right away, settling for 3-0-0 is okay. It is recommended to crosspath this tower once there is enough money to buy crosspaths for it.
 * 3-1-0: See 3-2-0
 * 3-2-0: On denser early-game rounds, this crosspath is generally better for the greater attack speed.
 * 3-0-1: More range can be useful, but it isn't normally the best option compared to crosspathing with Path 2 unless needing to specifically to shoot along a straightaway more reliably.
 * 3-0-2: Comes with built-in camo detection plus even more range. Similarly to 3-0-2, the extra range can be helpful if needing to shoot along a straightaway more reliably, but this misses out on extra attack speed.

Juggernaut

 * 4-0-0: The cheapest option to pop Leads with a Dart Monkey. Crosspath to either Path 2 or Path 3 depending on the needs of the defense.
 * 4-1-0: It has a bit more attack speed, but 4-2-0 should be bought for the Path 2 attack speed bonuses to make the greatest effect.
 * 4-2-0: More attack speed to shoot Juggernauts faster allows it to finish off groups of bloons more reliably.
 * 4-0-1: In itself, it is not very useful unless wanting to go for 4-0-2 for the camo detection.
 * 4-0-2: The cheapest option to pop Camo Leads with a Dart Monkey. Also useful for popping normal Camo Bloons along good straightaways.

Ultra-Juggernaut

 * 5-0-0: There is no point leaving this upgrade without crosspaths, unless on a custom challenge that restricts certain upgrades. Pick either Path 2 or Path 3 to suit the defense's needs.
 * 5-1-0: It has a bit more attack speed, but 5-2-0 is so affordable by this point that it's not worth leaving it just at 5-1-0 because of how much more attack speed on top of this upgrade could be done.
 * 5-2-0: The usual go-to crosspath for Ultra-Juggernaut. The Quick Shots and Very Quick Shots upgrades both provide extra attack speed, which allows it to throw Ultra-Juggernaut projectiles at a greater rate.
 * 5-0-1: Not as useful compared to a 5-0-0 and locks out Path 2's bonus attack speed. Only buy this if wanting to buy 5-0-2.
 * 5-0-2: Generally useful if along a straightaway and/or needing to pop Camo Bloons. However, external support such as Primary Mentoring, Stronger Stimulant already compensate for the range and Radar Scanner or Etienne Level 8+ already compensate for Camo bloons, as this crosspath will miss out the attack speed bonuses from Path 2.

Triple Shot

 * 0-3-0: Can be useful even without crosspathing. Can be used to pop early Yellow and Pinks along curved areas of the bloon track.
 * 1-3-0: Slightly more pierce per dart can be helpful at combatting denser bloon rounds during the early-game.
 * 2-3-0: If the bloons are quite dense, this is a useful upgrade to get for the early-game. Also pairs well with Super Monkey Fan Club transformation.
 * 0-3-1: More range can be helpful to let the Dart Monkey hit bloons further. It is worth upgrading further to 0-3-2 for the built-in camo detection.
 * 0-3-2: Effective early-game camo detection for all rounds. In addition, it has much longer range, useful for spreading the darts further, and can be more useful than the other crosspath in some cases.

Super Monkey Fan Club

 * 0-4-0: The most important part of this upgrade is its transformation ability to other Dart Monkeys, so it shouldn't be a problem if it is not crosspathed. However, to take advantage of its slightly extra base attack speed applying to its own transformation too, crosspathing this Dart Monkey is recommended to let this Dart Monkey itself become more effective.
 * 1-4-0: See 2-4-0
 * 2-4-0: More pierce is useful on denser rounds. Allowing its super darts to pop +3 bloons is more worthy over more range. Strangely, the extra range is not inherited with the transformation. Use Primary Mentoring to boost its range to compensate the lack of internal bonus range.
 * 0-4-1: Useless for the Dart Monkey's own transformation, as the transformation effect does not inherit range bonuses.
 * 0-4-2: The only thing making this crosspath useful is the built-in camo detection. The range bonus is not inherited with the transformed form.

Plasma Monkey Fan Club

 * 0-5-0: Crosspathing Plasma Monkey Fan Club is not essential, but it's worth crosspathing it to improve the main tower itself. All Dart Monkeys affected by the transformation will inherit their internal buffs, with exception of range (might be a bug, or could be intentional).
 * 1-5-0: See 2-5-0
 * 2-5-0: Extra pierce is helpful for the main tower itself. Allowing its plasma to pop +3 bloons is more worthy over more range. Strangely, the extra range is not inherited with the transformation. Use Primary Mentoring to boost its range to compensate the lack of internal bonus range.
 * 0-5-1: Useless for the Dart Monkey's own transformation, as the transformation effect does not inherit range bonuses.
 * 0-5-2: The only thing making this crosspath useful is the built-in camo detection. The range bonus is not inherited with the transformed form.

Crossbow

 * 0-0-3: Crosspathing this Dart Monkey is helpful, but it is not essential to make it useful in the early-game. In the uncommon case where it is necessary to quickly buy this upgrade for the 3 damage per shot, 0-0-3 is still acceptable.
 * 1-0-3: Crossbow already gains +1 pierce, but 4 pierce can be somewhat helpful in some cases. Gaining another +1 pierce allows the Crossbow to be slightly more effective against straightaways.
 * 2-0-3: If along an effective straightaway, the extra +3 pierce might be better than the attack speed provided by Path 2, more specifically on denser rounds.
 * 0-1-3: Leaving the Crossbow at 0-1-3 can be sometimes useful if not wanting to just invest fully into a Crossbow and only buying it for purely the better early-game.
 * 0-2-3: Normally better all-round, because more attack speed allows it to make shots more often and therefore can maximize its extra damage. Usually a stepping stone for 0-2-4.

Sharp Shooter

 * 0-0-4: By this point, the crosspaths of either path should be quite cheap in comparison. There is no reason not to crosspath it unless on a custom challenge that disables certain upgrades.
 * 1-0-4: See 2-0-4
 * 2-0-4: Against denser bloons, this crosspath can be better due to gaining an extra +3 pierce, but the rate of activating crits more often is generally better.
 * 0-1-4: See 0-2-4
 * 0-2-4: Generally better so that crits can be activated at a faster rate.

Crossbow Master

 * 0-0-5: There is no point leaving this upgrade without crosspaths, unless on a custom challenge that restricts certain upgrades. Pick either Path 1 or Path 2 depending on the Crossbow Master's positioning.
 * 1-0-5: See 2-0-5
 * 2-0-5: If along an effective straightaway, this crosspath can be better for the much greater pierce, but the rate of activating crits more often is generally better.
 * 0-1-5: See 0-2-5
 * 0-2-5: Generally better in almost all scenarios. With this crosspath, crits can be activated at a faster rate because the Crossbow Master will attack faster.

Strategy
Since each path focuses on a specific niche (Path 1 is Pierce, Path 2 is DPS, Path 3 is range and damage), you can crosspath to focus on one specific niche and have a little of another niche. But since attack speed (from Path 2) increases DPS (Damage per Second), most effective Dart Monkey crosspaths will have at least Path 2 crosspaths because it directly affects both Path 1 and Path 3 in Projectiles thrown per second.

However, there are some viable crosspaths that doesn't involve path 2. The 2-0-5 Dart Monkey is an example of this. Because Crossbow master gains massive pierce with this upgrade, it can be used on straightaways to crit a lot more bloons that the 0-2-5 could. This means that more bloons are affected by the numerous crits the Crossbow master deals more DPS on straightaways than 0-2-5.