[Overview]

Super bulky and fast
Makes a good check to Fighting-types, and has cool Ground and Toxic immunities
Reliable recovery is a godsend in NU
Awesome stallbreaker
Psychic and Rock weaknesses are bad
Faces competition from Mandibuzz for pretty much the same exact role, though separates itself thanks to its 4x resistance to Fighting and Bug (which Mandibuzz is hit neutrally by)

[SET]
name: Physically Defensive
move 1: Taunt
move 2: Roost
move 3: Toxic / Super Fang
move 4: Brave Bird
item: Eviolite
ability: Inner Focus
nature: Impish
evs: 248 HP / 228 Def / 32 Spe

[SET COMMENTS]

Plays as a defensive stallbreaker, able to wall offensive threats and Taunt defensive ones
Taunt is most important, as without it, Golbat can't really force anything out anyways
Roost for some nice, reliably recovery
Toxic helps Golbat break down bulky walls as well as set-up sweepers not behind a sub
Super Fang can be used instead to help further set it apart from Mandibuzz and serves as an alternative way of breaking down bulky walls
Brave Bird is used for nice STAB to keep from being setup bait, and it also handles Scolipede reliably without just Taunting it to keep it from setting Spikes

[ADDITIONAL COMMENTS]

Speed EVs to outspeed Timid Gorebyss before a Shell Smash to Taunt or Toxic it
Inner Focus is far more viable than Infiltrator, and is thus used, but can also be helpful against things like Fake Out Kangaskhan and Rock Slide Scolipede
Knock Off, U-turn, and Whirlwind are all viable options and can be used to fit your team's needs
Stealth Rock weakness can be a bother for a defensive Pokemon; spinners can be nice to cover that if you have room for one: shoutouts to Wartortle for Ice resist and a good matchup against most Rock-types and as probably the most reliable spinner, can also spin the Spikes that Scolipede can set against Golbat before Golbat can kill it
Seismitoad can take Rock- and Electric-type attacks aimed at Golbat while Golbat can take Grass-type attacks easily, while Metang can take Ice-, Rock-, and Psychic-type attacks for Golbat in exchange for Golbat taking Ground-type attacks!
Skuntank can take care of the Psychic-types that threaten it, and since they are both immune to each other's weaknesses that Poison-type shares, they don't compound weakness
Makes a good defensive core with a specially defensive Normal-type, such as Lickilicky or Audino, as it can take on Fighting-types that threaten them

[Other Options]

Golbat has a lot of good support moves that can be used as needed for the team
Specially defensive, though since its main weaknesses are usually special attacking types, Mandibuzz does it better
Nasty Plot set with awesome coverage options: Air Slash, Heat Wave, Giga Drain, Sludge Bomb
Haze, if Whirlwind's negative priority is off-putting since fastmon
Tailwind
Hypnosis, shit accuracy and Toxic is usually better for it anyways
Pursuit, but U-turn would usually be better in a slot for it

[Checks and Counters]

Nothing wants to switch into a Super Fang, so if you're running it, not much can beat it without taking up to half its health
Weak to Stealth Rock and has no passive recovery, so keeping up offensive pressure and never giving it a chance to Roost makes things difficult for Golbat
Not very specially bulky and has exploitable weaknesses, so you're best off targeting these weaknesses when trying to beat it
Psychic-types in particular take it on well since Roost doesn't remove its Psychic-type weakness (Jynx has two STABs to hit it with, Duosion doesn't care about Toxic, Gardevoir, etc)
Faster Electric-types only fear Super Fang on a switch or Toxic, making Rotom-A, Electrode (who can even outspeed and Taunt it to prevent Toxic/recovers), and Raichu good Pokemon to beat it
Ice-types can also play well against it, though most of them are slower. Still, Articuno can outspeed it and either Sub against a Toxic or Ice Beam it as well as Roost off Super Fang damage, Specs Glaceon will hit it really hard, and Piloswine can EQ it on a Roost or Icicle Spear it when it doesn't, either of which can 2HKO, though it has the potential to be Toxic stalled
Haunter is immune to Super Fang and Toxic and can even use SubDisable to get past Brave Bird and force it out