Honestly, I think Geten would make a really good opponent for Bakugo. Someone with a really cool, chill temperament would be perfect to contrast and conflict with his. And who more appropriate/perfect/literal than Geten ofc?
Ironically Geten was very egotistical from what I remember so maybe Bakugo with his wonderfully gained new humility will see a reflection (literally even with the ice) of himself vs Geten and realise how bad his ego was, but also to use it against Geten and come out superior? Bakugos explosives would be very effective against the ice too surely?
I'd really like to see this matchup anyway, I think this be an awesome way to have Bakugo face a villain solo who also challenges him as a character, makes him introspect more and thus develop even more as a person and hero.
If nothing else, it should be a literally spectacular and a funny nod back to how he teamed up with Shoto and Caimie to make that stunning ice slide and northern lights and I think fireworks display? That was such a beautiful and profound moment and a brilliant story arc and character development, Hori is seriously a genius at writing characters! He really understands his own characters well and how to make them interesting, nuanced, developed, sympathethic, morally complex and such!
Also, now I'm just remembering the jokes in the community about how Dabi and Geten were going to KFC or Starbucks or something whilst they were offscreen during their fight.