Will My UK Pokemon Diamond Wi-Fi with an American Pokemon Pearl?

I have a UK pokemon diamond, my friend is thinking of getting a verision of pokemon pearl which is from america.

I know that the american one will work on a UK ds..............

But will I be able to connect, trade and battle with my friends pokemon game if they are from different regions??

Yes, you can via wifi over the internet.

Maybe not so over a local ad-hoc connection - some games just don't.