Most powerful Pokemon in the metagame

[Suicune Rider]

The best Pokemon-who are they in your opinion(s)? For me:
Mewtwo: While not as undefeated as it was in RBY, it's still one of the best Pokemon in the game: it's bulky, super fast, hits like a truck (or lorry if your'e British!) has one of the best movepools in the game, and it that wasn't enough, it got TWO Megas this gen; not to mention it is almost impossible to wall due it's insane coverage and unpredictability.
Kyogre: While it's movepool is just OK, it has everything it needs, with not only amazing coverage, but also huge power and very good bulk even by Uber standards, not to mention it's Water Spout is the strongest move in the game due to rain and insane power; also great typing in Water.
Arceus: Do I even need to explain this? Best stats in the game, can be of any type, and an indescribable movepool!
Mega Rayquaza: banned from Ubers-self explanatory.

 

[skyradiant]

Ekiller Arceus is currently S+ Rank in Anything Goes, so there's that.

 

[Zeb]

Mega Rayquaza, Primal Groudon, Xerneas and Arceus. (Mega Salamence?)

If we talk non-Uber, Smogon tiers then I'll say Mega Altaria <3 totally not bias of me at all nope

 

[Jimmy 3 People 0]

Mega Gengar is completely unbalanced and unfair and you're a jackass if you use it. Which is exactly why I do.

 

[TeaWest]

To go along with Gengar, it's been OU since Gen I, which I think is rather special

For Ubers, M-Rayquaza fo sho

 

[Osprey]

Megaquaza's existence alone was enough to create an entire tier to allow for its use. Nuff said.

 

[Krash]

Speaking from a VGC Doubles standpoint, the current threat to work around is Landorus. As legends aren't allowed in competitive play, we can already exclude the Mega-Mewtwos, and with a smile on our faces. That thing is a wreckingball.

MSalamence is still a pretty decent threat, one that can easily be handled by an effective fairy type.