It seems the Template:Achievements is missing for BTD6 stuff. I have added a few achievements there, but it seems it's not finished yet. Is it okay if you finish up the Achievements in BTD6 section? I may be able to do all the other pages.
All of the Achievements I had listed were based on what I found on BTD6 Steam, so I assume it would be the same for BTD6 Mobile too, or so should be. It would be nice if it could be double-checked (though the currently only two secret achievements Big Bloons and Alcheristman and Bloonicle Boy are confirmed to be secret achievements)