Very interesting post and I hope you have fun doing these redesigns. Not the biggest fan of Galar's starters just as designs, but they are very fun to run in game. While I'd go with different directions for them, I'll try to stay in line with what Pokemon gave us.
Rillaboom I think could be Grass/Rock? We don't have many Pokemon with that combination and I think it can work with Rillaboom's gimmick of being a drummer.
Inteleon on the other hand is more tough for me to think on. I don't want to throw in another Water/Dark starter so I guess I'll suggest Water/Poison? Poison also fits the theming of Inteleon being a sniper and assassin, even if it's not as much as dark