Well, it depends on what Pokemon it is.
In Pokemon White and Black, Cubchoo will evolve into Beartic at level 37. You do not need to trade or use any items to evolve this Pokemon.
He does not evolve by level he evolves when u trade to another Pokemon black or white game
At level 59, it will evolve into Volcarona.
Swoobat does not evolve by level, it evolves by friendship.
Level 21
Throh doesn't evolve into Sawk at any level because it's not capable of evolving into Sawk.
Sandile evolves at level 29 to Krokorok and Krokorok evolves into Krookodile at level 40 (I f you don't want your Pokemon to evolve press b while it's evolving
Emolga does not evolve. I played Pokemon White also and it does not evolve. Some Pokemon do but this one does not evolve.
At level 36 Oshawott will evolve into it's last evolvution. Unless the player stops the pokemon from evolving by pressing the b button, the pokemon will then try to evolve again every level it gains.
In Pokémon White 2, Phione is not capable of evolving.
Grimer starts evolving into Muk at level 38, it is the same across all the Pokémon games.
He does not evolve.
In Pokemon White and Black, Cubchoo will evolve into Beartic at level 37. You do not need to trade or use any items to evolve this Pokemon.
He does not evolve by level he evolves when u trade to another Pokemon black or white game
You have to evolve it with its happiness level at 220.
At level 59, it will evolve into Volcarona.
he/her should evolve at level 33