Hmm... game changers (so you mean characters with totally unique fighting styles right?)
Well Dart is from a jrpg, so it would be interesting to see what would be put into his moveset
TigerShark is from a game similar to Pokemon
Toan has a plethora of unique weapons it seems
Joel and Ellie would fight together (not like ice climbers) Ellie would be circle attacks
Tag would use his kart, spray paint, and a paintball gun.
Coincidentally, I know none of those characters...