Ok, I think we can all agree the second gym leader is hard. No matter what Pokemon you have, it's nearly impossible. Here's what I've done so far to beat it:
I have gone to Slateport, and delivered the Davon Goods.
I've caught Pokemon like Minum and Ottish to help.
I've versed almost every person in Slateport and Dewford
And I still cant beat him. Does anyone have any strategies to easily beating him (Treeko was my starter)