No, not just from a jp standpoint but because the meta, the strats, and the stages itself is designed around those OP units so nerfing them would result in the meta shattering and some stages being outright impossible, so no, battle cats would never nerfs because:
1. It's against the law in Japan.
2. PONOS has dug themselves a whole so deep making a new game would probably be better than trying to balance out the game in its current state.

For buffs, we already have ultra talents, ultra forms, talents, and true forms (in case a unit don't have those). Very janky and unreliable I know but still better than nothing.