I was wondering should I trade an abra for a Mr. Mime or keep my abra to..

That depends on what kind of Pokemon you want. If you want a Pokemon that is very easy to train, get Mr. Mime. Since you traded for him, he will get a boost in Experience.

Abra, on the other hand, is very hard to train until he evolves, seeing as it only knows teleport. Also, after Abra finally does Evolve into Kadabra, you have to go through the trouble of trading it to get an Alakazam.

So I would say Trade, definatly. Even if you do want the Abra. You can always just catch another Abra.

Yes. Go and Trade your Abra for Mr. Mime. This is your only way of getting one unless you use a cheat device. There are plenty Abra or even find a wild Kadabra later on. If you do want to raise you abra to Alakazam... Kadabra only evolves by trading it to another player.

Really, you should do both. Abras are not extremly rare. They can be caught in the grass next to Cerulean Cave and you can pick them for a measly 180 coins each at the Game Corner. If you aren't up to Celadon City, or can't catch an Abra, just hold on to your abra. You can always go back again and Trade when you have caught another one.

hey, i have a question:if someone trades you an Abra, will it later on Evolve into Alakazam?

No he won't you have to Trade it again