Crobat
Pros
-Ridiculously fast
-Solid Attack
-Learns U-turn
-Aerial Ace is a decent move
-Can be good against Bruno, Erika, and to an extent, Giovanni
Cons
-Only decent defenses and HP
-Not too many options for physical attacks
-Friendship evolutions are a pain
Noctowl
Pros
-Great HP and Special Defense
-Decent Special Attack
-Can learn things like Extrasensory, Air Slash, Hypnosis, Reflect, and Shadow Ball
-Can be good against Bruno, Will, Erika, Koga, and to an extent, Giovanni
Cons
-Middling Speed
-Garbage Defense
It may seem like Noctowl is better, but I would choose Crobat. It's got a better typing, it's faster, and it can reliably deal with foes. Hope I helped!