depends which one you are talking about, but yes. unless ofcourse you are talking about the new Legend of Zelda Four Swords Anniversiry edition, on the dsi shop for free
You need to beat both games in the game pak (The legend of Zelda a link to the past and The legend of Zelda four swords). That's the only way to get in there unless you want to hack into your own...
It's a bit more strategic than its prequels but if you liked the minish cap you'll love four swords... and if you're a Zelda fan at all, this game is pretty cool...
yes, you just need a gamecube controller instead of a game boy advanced. You can't play shadow battle and you control all 4 links at once, but it is possible to play and win in four swords adventure...