You evolve it up with high friendship
You'll have to have it have high Happiness in order to evolve it.
how do you evolve golbat in pokemon blue rescue team
a golbat
how to evolve golbat in platinum.. how to evolve Scyther in platinum. how to evolve electabuzz in platinum. how to evolve magmar in platinum.
Golbat will evolve if it has max friendship with its trainer which means it can evolve at any level.
Golbat evolves into Crobat in Pokemon Emerald by full happiness.
There is no specific level for golbat to evolve it needs to be loyal to it's trainer in order to evolve.
Friendship
evolve golbat
friendship
Golbat doesn't evolve in pokemon red, blue or yellow. Generation II, and onward, if Golbat's happiness is high enough it will evolve into Crobat.
Golbat will not evolve in Yellow version.