ESC Key (Klefki) @ Eject Button
Ability: Prankster
EVs: 252 HP / 80 Def / 176 Spe
Bold Nature
IVs: 0 Atk
- Spikes
- Toxic
- Dazzling Gleam / Hidden Power [Fire] / Substitute
- Fairy Lock
This is a set I've been off and on toying with since the early days of SuMo UU but haven't been able properly use due to my more defensive style, which doesn't suit the aggressive plays needed to take advantage of this set.
The idea is simple enough, play it like a normal Klefki until you believe you're about to take a hit, at which point you click Fairy Lock and trap something just before Eject Button kicks in and allows you to go to the appropriate check and snag a KO (and yes it works on Dark Types), if played right you can do this twice in a single battle or get up some hazards if the opponent tries to dance around being trapped.
The choice between DGleam or HP Fire depends on how much you hate Scizor, meanwhile Substitute can ease the prediction required and helps toxic stall something down a bit.
As for the EV's, it has enough speed to get Fairy Lock out before Adamant Scizors Bullet Punch hits, with the rest dumped into HP and Defense because I'm lazy.
When used in conjunction with something like Scarf Nape you can easily pin down and remove things like lead Hydreigon, Rotom-Cut, and Scarf Krook to name a few, but requires good predictions to pull off.
Here's an old, outdated, and arguably irrelevant replay of the set in action against Shiba in a room tour. While the team wasn't any good and I ended up losing, Klefki still did it's job exactly the way it was built too.
http://replay.pokemonshowdown.com/gen7uu-554860882