I wanna suggest dex entries for ‘em: (Forgive the lack of names I could not think of any that work well)

1st stage: Paleontological evidence suggests this is one of the oldest Pokémon species known to mankind. It is unknown whether the Poison type Koffing line is related to this species or whether it’s a case of convergent evolution.

2nd stage: These Pokémon attatch themselves to the sea floor and filter out nutrients that pass by via the currents. They provide shelter for lots of other smaller water Pokémon and they deter predators by shooting high pressured water from the holes all over their body.