I have a pretty urgent question, and I hope this is the right place to post it! :S
I bought my boyfriend Guardian Signs for Christmas and it's just arrived in the post from Amazon, however it appears I accidently bought an American copy despite shopping on the UK Amazon. My own fault I know, but it wasn't made extremely clear at the time and I remember having a rough day.

It's already the 12th and if I'm going to even try and get a refund I need to do it soon, so I need to know if there's any way that the giving him the US version is going to effect the game play, or will it work exactly as it should?

I remember on my Shadows Of Almia game I got a Manaphy, a Darkrai and a Riolu, and if there's anything similar in Guardian Signs I'm worried they won't transfer to a UK copy of the main Pokémon games. There's also worry that it MIGHT be region locked and can't be played on a UK DS though they rarely are...
Please help, I'm an idiot and Googling doesn't give me many results.