You could find an exp. share to give your Pokemon if you don't want them to battle or you could send them out and switch them with another during a battle. Anything else, just battle as many trainers as possible and go to the highest level area you can find.
Level them up.
level it up to level 33
The Cerulean Cave. Besides Mewtwo, you can find pokemon up to level 67.
Level it up to level 16, and it will evolve into Kadabra.
You level it up to lvl 36.
Murkrow just like any other pokemon will level up when you battle against other pokemon and win.
you level can level up your Pokemon by given it an luckey egg when betteling
you battle with it or put exp. share and battle with a different Pokemon
the easiest way to level up your Pokemon to put it in daycare Pokemon will level up soon.Trade the Pokemon to friend and have it hold a lucky egg it will level up quickly.
Just travel with it and battle with it and level it up
Chansey > level up with max happiness > Blissey
you trade it while holding an up-grade.