Trading for Evolution.

[Monokuma]

Actually, it's possible to make a second save file, go to kevlar town to acces the PC and trade your pokemon between your two save files.
You have to use the GTS, though.

I really suggest this method.
Just make sure you're trading with yourself and not someone else when on the GTS.

Of course, you can trade with someone else, but this is a easier and less time consuming.

Have a wonderful day! 

Can you teach me how to do this?