>>149152429I think it's just because it would really bloat the number of characters. Most of the evil versions already got very few lines and screentime and Evil Gangle would be funny for like 5 seconds top when the joke about her not having an evil clone is funny enough anyway.
In-universe it's probably the fault of either Caine or whoever wrote the suggestion (probably Kinger since the game made no sense and he seemed really invested in it). If he just wrote "we play against evil versions of us" maybe Caine got lazy or straight up forgot about Gangle (lmao).