It needs a Moon Stone to evolve.
Munna does not evolve by leveling up. You need to use a moon stone on it.
You can use it evolve Munna into Musharna.
munna
you find it at the dream yard
use moonstone
Moon Stone!
Nidorina into Nidoqueen, Nidorino into Nidoking, Clefairy into Clefable, Jigglypuff into Wigglytuff, Skitty into Delcatty and Munna into Musharna.
munna evolves into musharma when you give it a moon stone.
The only Pokemon from Black/White you can evolve with a moon stone is Munna to Musharna.Otherwise, you can use a moonstone to evolve these Pokemon from previous generations while they are in Pokemon Black/White.Nidorina -> NidoqueenNidorino -> NidokingClefairy -> ClefableJigglypuff -> WigglytuffSkitty -> Delcatty
Munna Nidorino Nidorina Clefairy Jigglypuff Skitty
You can evolve Munna into Musharna by using a Moon Stone on it.
You can get Munna at the Dreamyard.