S Rank: Reserved for Pokemon who can sweep or wall significant portions of the metagame with little support, and Pokemon who can support other Pokemon with very little opportunity cost ("free turns"). Also the home of Pokemon who can easily perform multiple roles effectively, increasing their versatility and unpredictability. If the Pokemon in this rank have any flaws, those flaws are thoroughly mitigated by their substantial strengths. If there are suspects, they will come from this rank.
I’d like to propose a Pokémon for the S Rank. A pokemon that together with Kyogre controls the tier itself, and is such a mindless addition to any team that I can not understand why it isn’t S Ranked. Groudon. And here are my five justifications.
1. First off, Groudon holds a wonderful defense stat along with its good HP. It enables it, without any support whatsoever from its team-mates, take not one, but two swords danced extremespeeds from Arceus-Normal, the most terrifying sweeper in existence. With Stealth Rock up.
2. Drought is a perfect ability. Not only does it weaken the best move of the most popular pokemon in the metagame, but it also opens up great possiblities in team building. Ho-oh, Reshiram, Blaziken, would be much worse of without Groudon’s impact on the metagame. Spike stacking is a terrific strategy in the Ubers metagame. Ferrothorn, the Pokemon we all hate, is much easier handled when the weather is sunny, as even magic bouncers as Xatu or Espeon can OHKO it with a fire move.
3.Groudon is without doubt the best stealth rock setter in the entire metagame, perhaps barring Deoxys-Speed. It is all about opportunity cost. An Arceus forme can get rocks up with great consistency, but usually you want to use your precious move-slots for something other. No problem, Groudon always carries Stealth Rock by default, because it doesn’t really need more than its STAB Earthquake (which is the strongest one in the game), and share the remaining move-slots between Fire Punch, Stone Edge, Roar/Dragon Rail or Thunder Wave. There is no pokemon, except Deoxys-S, who doesn’t mind having to use a moveslot for Stealth Rock as little as Groudon.
4. Dialga and Groudon can’t be in the same rank. Take away Swords Dance+Rock Polish and Drought out of the equation and we have two very similar Pokemon, except Dialga is specially based with a different typing. Because the fact that Groudon has Drought, and Dialga don’t, they can’t be in the same tier. Now, I do understand that it doesn’t necessarily mean that these two Pokemon are exactly as good as each other, but the fact that Groudon has the a greater sweeper potential as well as an ability that both hinders the most common team Archetype in the game while simultaniously eases fighting one of the deadlies strategies in the game, as well as fueling incredibly powerful mons, all at the same time would mean that Groudon must be a rank over Dialga.
5. Versatility. Quoted from the definition of S-rank:
”Also the home of Pokemon who can easily perform multiple roles effectively, increasing their versatility and unpredictability.”
Not only is Groudon the best Stealth Rocker in the entire game, it is also a deadly sweeper, an effective lure (toxic Lugia), simply put: a Pokemon that can do a lot of things.
Even if Groudon has Stealth Rocks, one can not assume it to be defensive and therefore a misplay can be deadly.