this game is great...for about 3 hours
the first thing you do when you turn on this game is it asked you which trainer card do you want and you pick one then after that you have the option to play online, purchase clothes, transfer pokemon from your DS game, duel or battle (single player).
The online - its very boring, it only has the option of 3 vs. 3 or 4vs. 4 which is a double. it sometime takes forever to find an opponent and if you do he is either using very cheap pokemon or worthless pokemon. And there is also no leaderboard, so you could be battling for hours and days and it would be all for nothing in the end.
Purchasing clothes - you can purchase clothes to dress up your trainer to look pimpin' during a battle.
Transferring pokemon - you can transfer all the pokemon you have on you DS game, if you don't then you are out of luck and are only stuck with the sh**ty pokemon you chose at the start.
Duel - you can play with your friends...
Battle Colloseum - you can battle your way to the top (can beat the whole thing in a mere 3-4 hours if you have strong pokemon)
ok now if you have experienced all those, what to do next? nothing! that is pretty much the whole game, if you have beat the battle colloseum you have the option to battle online till you drop (which is fun for 1 hour max because it just gets too repetitive).
all in all, this game is a waste of time and money. if you do happen to buy it by mistake and want to return it, tell them its defective and get a new one and return the new one the next day and tell them your sister bought it for you for your b-day but you already have it. this worked for me, it should work for you too.