Golbat:
1. Nasty Plot
Golbat @ Life Orb
Ability: Inner Focus
EVs: 4 Def/252 SpA/252 Spe
Nature: Timid
-Nasty Plot
-Air Slash
-Heat Wave
-Roost/Hidden Power Ground
You might be thinking, "lolwut?!", but this thing can actually be quite worth using. While you might be drawn to its terrible Base 65 Special Attack stat, it is good enough to use Nasty Plot with. 229 Special Attack isn't very flashy, but after a Nasty Plot, that 229 Special Attack suddenly becomes 458, which is a whole lot more threatening. Golbat's defenses aren't the best, but they aren't terrible either (75/70/70 are usable, considering his good resistances). Poison/Flying is actually quite a good defensive typing (albeit the Stealth Rock weakness), boasting a resistance to both of Venusaur's STAB while not being Registeel is pretty fantastic (If you can avoid Sleep Powder, it is a great check to Venusaur). It can also switch into Close Combats fired by Hitmonlee and stuff with its 4x resistance to Fighting.
Golbat isn't lacking in the Speed department either, Base 90 is tieing with Moltres. Onto the attacks, Air Slash is for STAB, and Heat Wave provides pretty good coverage alongside it. Roost for recovery and Sucker Punch dodging, but Hidden Power Ground lets you hit stuff like Aggron.
2. Brave Bat
Golbat @ Life Orb
Ability: Inner Focus
EVs: 252 Atk/4 Def/252 Spe
Nature: Jolly
-Brave Bird
-U-Turn/Hypnosis/Super Fang
-Taunt
-Roost
Number 2 on the list, but certainly not in terms of viability. Pretty much a Crobat-lite, this thing can dent things, scout, Taunt, and pretty much do everything. Base 80 Attack may not look like much, but LO Brave Bird still hurts quite a lot. U-Turn allows you to scout, Hypnosis is meh, but Super Fang can soften walls for you. Taunt + Super Fang pretty much destroys shit like Registeel and Chansey. I don't think I have to go over Crobat's resistances and ok defenses again, right??