>>43556111At level 41, those are the last 4 moves Mightyena learned by leveling up. For some reason Gamefreak uses that system a lot despite it being absolute dogshit. It's also the reason why Sharpedo doesn't have any STAB moves
Sharpedo gets Crunch at level 22, which is then replaced by Screech (level 28), Slash (level 33), Taunt (level 38) and Swagger (level 43)