Can't complain about Aegis being gone, but due to it's immense role compression, pretty much every team out there is now obsolete and we're going to have to find new ways to combat speedy versatile attackers like Pheromosa and Latios, as well as powerful offensive nukes like Tapu Lele and Magaerna. Obviously we have our Mantines, Ferrothorns, Celesteelas and such already to stave off what I feel will become a much more offensive metagame now that set-up sweepers no longer have to deal with the headache of beating out Aegislash in a 50/50, but I'd like to speculate on a few sturdy defensive mons who are now unlocked with the absence of Aegislash.
Lati@s is still a thing in the meta, but everyone and their mothers can tell how much their effectiveness declined due to it's inability to carry a coverage move that can touch Aegislash reliably. Now they can make use of their incredibly diverse offensive and support movepools. The Tapus are still going to make life difficult for them, but I feel they have the potential to become premier pivots.
Clefable, like the Latii twins, is still being ran, but was greatly neutered with Aegislash on every team. Genesect is still a problem, but now it can actually reliably serve as a glue mon without the opponent being able to switch to that Ghost-Steel every time Clefable came in and hindering it from doing its job.
Slowbro is a big winner as it offers a sturdy water, steel, and fighting resist off Regenerator. New threats like Bulu, Koko, Genesect etc are potentially very hostile to Slowbro's presence in OU, but the various fighting and steel types that are enabled by the loss of Aegislash, especially when the likes of Mega Lopunny are eventually available will likely cement this thing a place in the meta.
Jirachi is a bulky versatile steel that was suppressed by Aegislash but will likely take on many of the roles Aegislash used to fulfill. Losing the fighting immunity is huge, but it will likely do very well with all the fairies out there, many who will spike in usage with the sword and shield gone. It also offers a variety of team support options like Stealth Rock and Healing Wish.
Mew is yet another bulky Psychic type that cries tears of joy without the sword and shield bullying it with the Sub-Toxic set. It can serve as both an answer to the incoming rise in Fighting-types, Psychic-types and the like while simultaneously being a potent stallbreaker.
Dhelmise/Decidueye offer numerous resistances thanks to their rare but desirable typing and hazard removal options. Jury is still out on which is better (though I'm leaning towards Decidueye due to access to Roost based on what I've seen so far) but I feel that one of them will find a solid niche in the tier against the powerful water, fighting, and electric types that inhabit the tier.
EDIT: On a side note, while most of these mons can check a good chunk of the powerful attackers that inhabit Pokebank OU, each and every one of them get walked over by Pheromosa with ease. So yeah, chances are we'll be getting quickban #3 in the near future.
