Sutpididot

Idk If I'm gonna be able to beat him my current plan of action is to lvl my follow pokemon to lvl 35ish. 2 Sandslashes. 1 Onix. 1 Gravler (Or His Evolved Form). The strat is to use Gravlers Mudslap on each of them then switch to a sandslash for dps when he sends out his eltrcoballs I'll tank the hits with Onix also bringing a spare lvl 40 incase. Think I can win? Idk. Posting this becuase I'm not sure and Idk if theres a way to ask for help.