(WARNING: If do not have these kind of pokemon, than read another answer or GET THOSE KIND Of POKEMON!) So, hi.O.K., so you need to get your strongest pokemon first (anything over 60). If you don't have a pokemon over 60 then stop reading and look at another answer or get pokemon over level 60. Then keep pokemon from these types...
Any other type that you're good at using (Optional).
Than take away one of these types (or if you didn't add another type then skip this). Use one pokemon of each of these types. (Suggested pokemon for each type: Water, Blastoise Grass, Venasaur Fire, Charizard Rock, Golem Psycic, Alakazam Electric, Jolton/Raichu)