When does tranquil evolve?

Answer 1

Tranquil evolves into Unfezant at level 32. You can also get Unfezant in these locations:

winter: Lostlorn Forest-rustling grass and route 12-rustling grass.

spring/summer/autumn: Lostlorn forest-rustling grass, route 12-rustling grass,

route 6-rustling grass, route 7-rustling grass and

dragonspiral tower-rustling grass-surf required.

this answer is by your Pokemon helper, Mig. PeAcEs PeOpLe!

Answer 2

Lvl. 32