I have a Grovyle and Taillow, just beat Brawly. Now I'm thinking about Mauville, and I want to catch all my own pokemon. And they all must be Ash's current PKMN. How can I beat Mauville Gym?
I suggest that you train your Grovyle up to learn the move screech. Then teach it a super effective move against his pokemon. I used this technique and it worked very well.
Well since electicity isn't much good against a grass types, and you can't go get a phanphy, uh I say do what Flareon22 said. Don't use that Tailow, but I think you already know that
I just hade my Grovyle Leaf Blade the hell out everything. Leaf Blade will 2-5hko his Magneton, but he'll prolly just use a Super potion, unless you made him waste 'em all.
Trust Me an Ash team is a nice way to keep the game challenging but why not make your own really good team....Have your own original team trust me its much more fun that way!