Squallx19

Hi guys, i have a trouble, im in kanto and i have a charizard(65), golduck(58) and pikachu(54) (they are my high lvl pokemon actually) and i go for Blaine the fire gym, i cant defeat him with ny golduck, so i want u say me where i can go to level my pokemons because i go to cinnabar mansion to level but in this place the pokemons give me very little experience. So help me if u can. Thank you and sorry for my english is very bad xD.