There is something like that. It's called a game shark. Sorry, no idea where to buy it.
go to gamestop and ask the people there for it. or just google action replay for gameboy sp
Go to game stop
i was looking for the same answer and i found out on yahoo answers. a normal original one will but max and duo wont.
You can trade pokémon by using a link cable between your GBA sp / GBA.