Hi, i am trying to beat Maylene the gym leader but i do not know how.I know how to pass the puzzle but idk how to beat her.So anyway here is the team i use and i try to beat her:
Grottle lv 24
Ponyta lv 24
Buizel lv 24
Luxio lv 23
Staravia lv 26
(saving for a riolu which i used in my other pokemon diamond game)
I need to know a good place where i can train so is there any help?

If your losing train your teams to be of a higher level. I mean you got the VS seeker, right? Use it.

Maylene is the Gym Leader of Veilstone City’s Gym, known officially as the Veilstone Gym. She hands out the Cobble Badge to Trainers who defeat her. She specializes in Fighting-type Pokémon.

http://bulbapedia.bulbagarden.net/wiki/Maylene

take your pokeballs and chop them off.