>>50171804Baby Pokemon have never served a good purpose in story play. You always get them too late which forces you to grind their levels.
In competitive play, Little Cup, most of them are way too weak to compete with the better preevos. Only Munchlax, Elekid, and Mantyke have ever had a semblance of viability.
Baby Pokemon never made sense as a distinct type of preevolution. It's always just been extra effort for no reward. And if all you'll do is lock exclusive level up moves behind them, you still have the same deal: extra effort, just for the sake of making them not useless, but not introducing anything anyone wants.
Baby Pokemon the more you think about it was a marketing invention first and foremost that was then carelessly fitted into the game's mechanics. Marill and Azumarill were already shitmons, they didn't need Azurill to "balance" them or whatever. It's garbage whose only reason for existence was to attempt something funny with the mechanics, and try to cash in on the cuteness factor of Pikablu.
They never made more baby Pokemon until gen8 because it was understood that it was a worthless gimmick that clogged up the dex.
As it stands, baby Pokemon should be mechanically no different from other early route mons with the only distinction being they evolve via happiness---so essentially, Budew.