With Greninja gone, who's going to pick up the slack?
Well, Keldeo, who else? It went from #12 to #3 in one short month... and keep in mind, Greninja was only banned a third of the way through the month, so #2 may be achievable in a full month without Greninja. #1, though... nope. Landorus-T looks more untouchable than late gen 4 Scizor at this point. It's used so much that it's kind of funny that it hasn't been suspected yet. I think the reason starts with "91" and ends with "speed". As for the Dark side of the equation, Bisharp is also on the rise, from #11 to #6. It's amazing how, for a game where debuffs are typically terrible, a Pokémon centered around countering debuffs can be so great. If you ever wanted to see just how dominant Stealth Rock used to be, a move that serves the purpose of countering it manages to be just this ubiquitous despite giving a free +2 attack boost to a top 10 Pokémon. Intimidate being turned from a -1 to a +1 also helps a lot, which is great when it's the only ability the most common Pokémon on the ladder can pack. I guess it's also part of the reason why Sticky Web, once slated to be the best non-Fairy new gen 6 move, is such a non-factor nowadays.
Also of note is the interesting rise of Slowbro, from #19 up to #14. I'm assuming it's also partly collateral for Greninja going bye-bye. I just want to point out that whereas the Mega variant was slightly more popular last month, the Regenerator set comes out on top rather comfortably in January. Still, Mega Slowbro is far from the non-factor I and many others expected it to be - if nothing else, it does the Calm Mind schtick a lot better than the regular form, Regenerator be damned.
Who would've thought Lopunny was going to be such a powerhouse? The "new and shiny" factor is pretty much gone, and Lopunny is still going up (#29 to #21)! Guess the world was just crying out for a Scrappy Fighting-type more competent (and especially faster) than Pancham, huh? Can't say no to STAB Fake Out, either. Sableye, Altaria and Diancie are keeping up the pace... can't say the same for Sceptile and Swampert, though. Rain teams took a pretty big step back this month, and the new premier abuser really suffered as a result. Beedrill also came crashing down, so a promotion to OU is just about impossible at this point. The increased competition for that mega slot gives a much bigger opportunity cost to any and every mega, and it's becoming really obvious.
Another result of this is the fact that both Heracross and Pinsir were demoted to UU. Remember when Aegislash was banned, some people argued it shouldn't because it was the biggest check to Pinsir, Heracross, Gardevoir and Medicham, and those four would rampage with Aegislash gone? Fast forward a couple of months, and Gardevoir is the only one still in OU. Of course Gallade is a pretty big deterrent when it comes to Medicham, but it took a pretty sharp drop itself (#34 to #44). Guess Lopunny really is the king of Fighting-types, huh?
One surprise arrival in the OU tier is Raikou (up from #54 all the way to #35). To be honest I'm not really sure why it got so popular so quickly, because Zapdos is as popular as ever and Manectric and Thundurus-I also got a nice boost this month.
...you're wondering if I forgot something, right? Of course I didn't. January 2015 will go down in history as the month where Contrary Serperior was released, and after many, MANY tiering changes through the month, it looks like UU is where it'll be making its home after a quickban from NU and a suspect test in RU. OU? Unfortunately that's a little high, it came in at #43 this month despite being one of the most anticipated events ever, although there's the fact that it wasn't available for the first week of the month to consider. Theorymon about the best moves to put on it turned out to be off in many cases - I've seen some people say either Glare or Knock Off was an absolute must instead of being stuck inflicting paper cuts on the likes of Mega Venusaur, Talonflame or Heatran, yet in the end the non-Leaf Storm/Dragon Pulse slots were better filled by Hidden Power Fire or Ground, Giga Drain and even Substitute. In the end, the poor thing was done in by the fact that if you want to do anything, you MUST use Leaf Storm on your very first turn, because 75 special attack is absolute garbage, and I'm pretty sure not even an unboosted Hidden Power Ground against Heatran is going to do an awful lot, relatively speaking.
In ubers, Groudon outranks all of Arceus' forms put together for the second time in a row, and Ground is actually the second most common Arceus type now simply because it's Primal Groudon's only weakness. Speaking of that monstrosity's weaknesses, the Blue Orb is still bog standard on Kyogre just to get rid of the Desolate Land-acquired immunity to Water, even though it's likely suboptimal against just about everything else.
If you ever wanted an idea of how grossly overpowered Mega Salamence is, it's a top 5 Pokémon IN UBERS. It beats out the likes of Darkrai, Lugia, Yveltal, Mewtwo... oh right, Mewtwo is all the way down to #9 now. Anyway, Mega Salamence is also great against Primal Groudon, thanks to a handy immunity to Earthquake and Precipice Blades, a resistance to Fire Punch and Lava Plume, and Intimidate shenanigans to boot. Really, Mega Salamence was a mistake. The one reason why it was well out of OU was because Dragonite existed, not because it was a bad Pokémon on its own. I'm pretty sure that eventually, the power creep (and maybe the increasing opportunity cost of using a specific mega) is going to catch up to most of the currently banned megas (Kangaskhan is admittedly easier to deal with because Parental Bond itself can just be nerfed) at some point in the future. Salamence on the other hand... it's going to take a long time.
A quick look to AG while I'm at it... well, it's a bit more varied than last month. Rayquaza and Klefki both dropped sharply - guess people were just sick of their Mega Rayquazas dying to Swagplay. Groudon and Kyogre usage is also down, while most other Pokémon (except those with Magic Bounce) had varying increases to their percentages. The big winner this month, though, is Talonflame. Yep, even when there are no rules and no banlists priority Brave Bird is just as much of a terror as when all the rules and banlists are there.