OU Growth Whimsicott Sun team. Whimsicott uses Growth in the sun to get +2 SpA. Between Solar Beam, HP Ground, and Moonblast, and Chlorophyll, you outspeed and OHKO a significant majority of the metagame, especially after rocks, including scarf Kart, scarf gren, all offensive tapus, defensive Lando, 2HKO fully SpDef Pex, etc. Once sets up, it's very difficult to stop.
http://pokepast.es/a1ccf7b4a8edd0ab