Share some battle tactics here!

Here's one:

Learn a fighting-type Pokémon the move Karate Chop, which has a high chritical hit ratio. Learn it the move Focus Energy as well, which raises the Pokémon's chritical hit ratio. Then, before battle, give the fighting-type Pokémon a Dire Hit, an Item that raises the chritical hit ratio of one Pokémon.

Once you begin a battle, your chances of making chritical hits are almost doubled!