i use:
Cherrim - for its ability so my other pokemons gets higher attack and speciel attack : D
Nuzleaf - cos it can use explosion and take some of my oppenents pokemons out in one hit while im protecting on the other pokemon xD
Weepinbell - theres no reason why i use it.. only that i think its cool and it was that sunny day ability ^^
Tangela - cos of its sunny day ability and for a baby pokemon it have high stats... i think its becouse it was a non-evolution in some of the games ^^
Charmander - cos its fire and fire type moves doubles in sunny day ^^
Castform - cos it can do moves like icy wind and stuff ^^

and yeah its a double team