For me, that would kind of take it from "heh, cute touch" to "why does this exist?" territory. They
might be able to pull it off with good character designers, but it still has a high potential for some cursed stuff, and you run into problems like:
- IIRC, Kirby is canonically a baby, so baby Kirby is just Kirby.
- Similarly, baby Pichu is just Pichu, baby Squirtle is just Squirtle, baby R.O.B. is just R.O.B., and baby Pyra/Mythra are just Pyra/Mythra.
- I suppose these instances could be played off as "that's the joke".
- Bowser Jr.'s design is almost the exact same as Baby Bowser's design, so what the heck would baby Bowser Jr. even look like?
I guess on the bright side, baby Piranha Plant just being a sapling in a pot and baby Steve just being smaller would be pretty funny, and baby Duck Hunt would be absolutely adorable.