Ditch Mean Look. Overall, it's much more practical to have an attack instead. As Crobat's base Attack is higher than it's base special attack by 20, you might want to concider X-Scissor (Bug, power 80, ac. 100). If the type doesn't appeal to you, you probably would have to resort to a special attack move like dark pulse or giga drain
Here's the advantages of your move types (plus suggested types)
Fire grass, ice, bug, and steel.
Flying grass, fighing, and bug.
Bug grass, dark, and psycic.
Dark Psychic, Ghost
Grass Water, Ground, Rock
As you noticed, you have a ridiculous super effective coverage against grass, and not that much else.
Disadvantages of your move Types
Fire Fire, Water, Rock, Dragon
Flying Electric, Rock, Steel
Poison Poson, Ground, Rock, Ghost, Steel
Bug Fire, Fight, Poison, Ghost, Fly, Steel
Dark Dark, Steel, Fight
Grass Fire, Poison, Steel, Grass, Flying, Bug, Dragon
You're pretty well rounded whatever you choose. Although weakness to steel may seem alarming, it's alright as fire is super effective. You're a little limited when fighting fire Pokemon, but the only one you'd really be in bad shape against is Heatran, and we don't fight Heatrans everyday ;).
For your moves, if you don't take a fancy to how bug coordinates with your other moves, you probably should go for dark pulse as it can combat psycic, which is super effective against you. If you're into regaining health, giga drain would work even though it's only power 60 and is not very effective against a lot of types as it helps you combat rock, which also is super effective against you.
Overall, I like your Crobat, just replace Mean Look.