Playing against someone in a higher League than you will earn you bonus rating. You get 1 extra rating point for every League above you your opponent is. E.g. if you're in Silver League and play against someone in Diamond League you will earn 2 extra points.
The League bonus applies to Quick Play and 2 vs 2, but not Friend games.
2 vs 2 Clan Rating Bonus
If you play a 2 vs 2 game with someone from your Clan you'll gain 25% bonus Clan rating.