>>26740363>>26740617These. Starter Pokemon (and Pokemon in general) learn plenty of moves just for coverage that don't match their typing.
There's a good chance Popplio will remain a qtpa2t, though, looking at the other Pokemon that learn it. The move has to do with the opponent suffering emotional damage by hearing the Pokemon shriek, like most people would when hearing a baby kitten cry out. It's hard to do that if you're not charming.
Ironic considering the fanbase's lukewarm response to Popplio.