Rain is really poweful, I expect there will be some changes in the future to balance things a bit more. Im glad to see Amonguss doing so well in the OU metagame.
Sun has got a bit of a boost but running a sun team is just so hard with rain so popular at the moment, however subsplit Ninetales is really good.
Ninetales @ Leftovers
Nature: Calm 252HP/108Def/148Spdef
Been using this set and it works really well, even managed to stall out a politoed but that was when sun was up.
Another pokemon who really works in the this current metagame is sub Hydreigon
Hydreigon @ Leftovers
Nature: Modest 56HP/252SpAtk/200Speed
-Focus Blast/Earth Power
Iv been using this pokemon in sun and it works great. Can 2hit ko all the members of the new popular core of Heatran/Amonguss/Slowbro. Also does well agaist some of the other pokemon in the current top 10