With that particular spread... Crobat 3-hit KOs Standard Blissey (252 HP) after 3 Nasty Plots with HP Fighting, 4-hit KOs Bliss with Air Slash. Blissey strikes back with T-Wave, Bolt/Beam or its array of set-up attacks.
Thats why I tend to ignore Crobat's Sp. Attack. Even with maxed out Sp. Attack and using the most powerful attack it can vs Blissey, it can't take out the most common Sp. Wall without 4 turns of flinch-hax... if you somehow managed to get 3 Nasty Plots in a row.
I think its a great pokemon, but... you really need some sort of anti-bliss strategy. Taunt might help, but then that removes another attack.
Couldn't be more dead on. Bronzong is also another huge problem, resisting Air Slash and being Immune to HP Ground.
After testing this thing out the last 2 days on Shoddy I find that its capable of destroying teams. Most users expect a trapping Crobat rather than a Special Attacker. In order to bring out this Pokemon's effectiveness the best strategy would be to use it in conjunction with Magnezone running Explosion. Then again any Pokemon can be successful with a good supporting team. Beware of steels!