Support Characteristic
A Pokémon is BL if, in common battle conditions, it can consistently set up a situation in which it makes it substantially easier for other pokemon to sweep.
I am nominating Crobat for BL because of the support characteristic.
Crobat (M) @ Leftovers
Ability: Inner Focus
EVs: 4 HP/252 Atk/252 Spd
Jolly nature (+Spd, -SAtk)
- Brave Bird
- Taunt
- Roost
- U-turn
The standard Crobat set is very predictable, and yet it continues to retain high usage. Even as more and more countermeasures are taken against it, such as a large increase in rock and steel types, who even then are hard pressed to break Crobat, the standard set is still able to fulfill its purpose of setting up other sweepers.
The way Crobat is able to set up other sweepers is through the use of Taunt and U-turn. Taunt, backed by Crobat's 130 base speed, the second fastest in the UU tier, is able to prevent entry hazards, stat ups, and recovery moves from nearly every pokemon in UU, barring Electrode and possibly other Crobat. This, combined with the fact that the only pokemon able to consistently take Crobat's assaults are easily exploitable steel and rock type walls, allow for easy entry for many of UU's most threatening sweepers such as Blaziken and Shaymin.
With U-turn, Crobat further helps its team mates by repeatedly wearing down the opposing team while also preventing recovery, giving team mates a much easier time sweeping. The damage caused by entry hazards and U-turn can weaken enemy walls, while they are not able to accomplish much at all besides weather Crobat's attacks. These so called Crobat counters, such as Regirock, Registeel, Rhydon, or Kabutops, are forced to take damage from Crobat while not being able to accomplish the tasks they came in for such as setting up entry hazards, walling other pokemon, or significantly threatening the opponent's team. U-turn is also able to scout for switches, giving control of the match to the Crobat user no matter what.
Roost, it's excellent resistances to Bug/Fighting/Grass attacks, immunity to ground, and respectable defenses (able to take Ice Beams and some Stone Edges while Taunting and Roosting afterwards) gives Crobat the longevity it needs to do it's job consistently throughout the entire match. Also, Crobat's call for being put up for suspect once again is supplemented by the offensive characteristic. Crobat, through the use of only Brave Bird on the standard set, is able to take out a ridiculous amount of UU's most threatening sweepers, such as Blaziken, Shaymin, Mismagius, Swellow, Roserade, every single UU/NU fighter and Espeon in one shot. Crobat's sweeping abilities is helped by the fact that most of it's counters do not have recovery from residual damage and U-turn, so it is able to wear down the opposing team and pull of a sweep all by itself.
Shaymin
Peachfuzz: Crobat, Borderline Accepting. Would've liked to see a bit of elaboration on how each aspect fit into the characteristic.