Need better fighting types

This has been an issue pretty much since I started playing this game. I’ve got Lucario but every other fighting type I have is absolute dog water. I’m at stage 510 (Snorlax) and every normal type stage is a nightmare that I have to face with lucario, sawk, hariyama, and hitmonlee. How are you supposed to get better fighting types besides them randomly showing up at special stages? This is awful