Or:Turn one: Crobat used Taunt. Regirock used Stone Edge.
Turn two: Crobat used U-turn. Player switches in Shaymin. Regirock used Stone Edge.
(Beaten!)
That really isn't dealing with Crobat. You've hit it once with Stone Edge, and then done very little damage to Shaymin (for example) who is threatening to KO you if you don't switch. Unless you have a second SR user, which people rarely do, then you have to rely on Regirock to get back in to set up SR's. I would not hesitate to Taunt Regirock in any situation I came up against him in, knowing that I could always switch in something next turn to threaten him giving me (the crobat user) the upper hand in the battle.
I also haven't even mentioned you'd be relying on a move with 80% to deal with Crobat. That's no guarantee.
Turn 1: Crobat Taunts, Regirock Stone Edges.
Turn 2: Crobat U-turns, gets predicted, and Shaymin gets hit with Ice Punch.
Turn 3: Shaymin Seed Falres (which also has a significant chance of missing), Regirock should hang on (if it's holding Leftovers; if it's Choiced, then Regi's screwed), and KO's with Ice Punch.
That's the problem with Crobat right there and is why I feel it doesn't need to be moved up to BL; yes, it has U-turn and Taunt, but that doesn't necessarily mean anything other than making sure you won't get stat-upped on the switch-in, or hit with a status move. It doesn't stop you from getting predicted and hit with an attack. The situation with Regirock isn't the best example, due to Specsmin dealing with it regardless, but the points still there.
Plus, again, this is just Regirock. There's also Rhydon, which works similarly. Then there's Electrode, which can T-Wave it, crippling it, then go wherever from there. Then there are the Scarfers, which, since they're viable sets regardless, and aren't sets that have to be forced to beat Bat, there shouldn't really be any problems with using them.
Then there's again how Crobat works. All it does is prevent is switch-ins from being statused with Taunt. It doesn't support them much beyond that though, or guarantee them a safe switch-in, since the switch ins can still be predicted and hit with an appropriate attack, which doesn't even require a Scarfer, just a bulky attacker. Since Crobat doesn't actually make it's teammates broken, nor does Taunt give it an irrecoverable, undeniable, or unworkaroundable advantage due to this fact, I don't really think it needs to be moved up to BL.