Unfezant evolves from Tranquill at level 32, so, normally is not possible to encounter it under that level in the wild. But on Lostlorn Forest is possible to find it at Lv.22.
It has 5% Encounter Rate (Rustling Grass) and 11.94% Catch Rate.
NOTE: is also possible to catch an Underleveld Unfezant on Route 6 (Lv.25, through Rustling Grass during Spring, Summer and Fall) and on Route 7 (Lv.25, through Rustling Grass during Spring, Summer and Fall).