A coral pokemon is a nice concept, and Corsola has a pretty cute design - kind of like a coral Chansey - though the more you think about actual coral, the stranger this thing gets. The hard, external part of a coral is just the skeleton secreted by a colony of anemone-like polyps. Does Corsola have polyps? Maybe just one big one, like a mushroom coral? Is that what its face is? Or is the pokemon basically a coral skeleton with a face? Apparently Corsola can even form reefs. Does that mean they'll just grow together in fused, stationary piles like actual coral? Non-pokemon coral would also have to exist in this setting for its marine ecosystems to function, and I'm pretty sure we've seen it fairly often, the one exception to the franchise's "no normal animals" rule.

Corsola just needs a nice evolution into a big multi-faced coral colony, or something.

Corsola raises some questions, but it's cute.