I remember last gen I used this Togekiss set, which I planned to write an analysis for but was too lazy. It seems like it still has a lot of potential this gen though:
Togekiss @Leftovers
EVs: I don't remember, but I know it had 252 HP and a lot of Special Defense
Calm Nature
Serene Grace
- Substitute
- Roost
- Toxic
- Air Slash
People really underestimate how deadly Toxic + Flinch can be. Taking an attack as well as poison damage while not being able to do anything back for a turn adds up really quickly. While this Togekiss isn't necessarily the best thing to use against offensive teams, it rocks a stall team's world.
Because so many members of a stall team are slow, they're susceptible to flinchhax from Air Slash. A lot of the members aren't strong enough to break Togekiss's Substitutes either, since Togekiss is quite the bulky fuck. When they flinch, it means that they can't recover their health, while they're taking a lot of damage in the process.
Basically this set is a lot like SubRoost Zapdos. The only difference is that Zapdos deals with Steel-types better, but Togekiss is a better overall staller thanks to Air Slash. Of course, if you have Toxic Spikes support on your team, that's actually irrelevant, since Togekiss now has the option of dropping Toxic and putting Flamethrower or Aura Sphere on the set, although it might not be the greatest idea in case you come across a wall that's invulnerable to Toxic Spikes.
I think that SubRoost with Flinch is going to be Togekiss's best niche this gen, because seriously, Shaymin-S does the boosting sweeper thing better with Growth on steroids. Stoned Togetic is a better PlotPasser due to much more bulk, not to mention Volbeat who passes Tail Glow and has an easier time doing so. Jirachi is a much better ParaFlincher IMO, because he can come in and do the job more often, with a 100% accurate STAB. Togekiss might have Encore going for him, but Volbeat might be better at that too thanks to Mischievous Heart.
SubRoost with Flinch is something that only Togekiss and Dunsparce can do, and it's pretty obvious that Togekiss does it better. Therefore, it's a niche that he can call his own in OU, so I personally think he's gotta try and abuse it as much as possible if he wants to have a reason to be used.
Honestly, it's a real pity that Togekiss didn't get Agility or Calm Mind, because it really needed one, the other, or both to be a much better contender in OU.