Go to either western cave(best)or silver trench.if you have a pokemon which knows either heatwave or earthquake go to silver trench,their are lots of monster houses there it should be easy to level up.best place is western cave(tons of strong pokemons).i went with a charizard(53)and blastoise(48)when i came out my charizard was lv60 and blastoise was lv56.second time i went charizard grew to lv67 and blastoise grew to lv64.i hope you liked this tip