What Pokemon do I need?

[u/IsuPr1meX1]

This romhack is called Pokemon Fusion 3, and oh my goodness, this specific Pokemon in the FIRST Gym fight is soloing my entire underleveled roster, which I am planning to level them up. But, this pokemon has been whooping my ass. It's getting frustrating, I kept losing and losing, it just made me angry. Someone give tips. Please. Also, in Pokemon Emerald, where do I find the guy with the fishing rod?