If you haven't played this with four GBAs, you really should try!
I've been trying to have monthly game/movie nights at my place the past little while, and for our first "Retro Nintendo Night" for the NES's 25th anniversary, we played three multiplayer games from each Nintendo console. Wanting something unique for the GameCube, I dusted off Four Swords Adventures (which me and my brother only played through once with just two players), and borrowed two more GBAs and got one more GCN-GBA cable (I had three already despite having only two GBAs...). At the party, we played the Shadow Battle versus mode with a full four players, which was frantic fun, and probably one of the best highlights of the evening, since no one in the room had played it that way before, and most people hadn't played it at all. I was getting comments the next day about how fun that particular game was - one of my friends said he dreamed about it. 0_0 We only played it for half an hour (because we had fourteen other games to get through), but maybe one day I'll round up some friends and get through the main adventure again.
A friend who is moving decided to clear out some stuff he wasn't using, so he gave me his GameCube - now I have two! I've seen that you can use the GBA end of the GCN-GBA cable with a GameCube equipped with a Game Boy Player (as if it were another GBA), with the GCN end connected to another GameCube (or the Wii, I suppose, so I guess I already could have done this). Since my TV can do split-screen, that might be a neat thing to try, I just need to find a Game Boy Player on eBay for cheap one day. I'm still waiting for the Freeloader disc (that lets you play import GameCube games) I ordered two months ago from Play-Asia.com (grrr) so that me and my brother could play my Christmas present to him - DreamMix TV World Fighters - but once I have that Freeloader, I might be tempted to pick up other Japanese GameCube games, like the Japanese version of Four Swords Adventures which has the "Tetra's Trackers" game that was cut out of the North American release. Assuming I can figure it out, it sounds like an obscure thing a hardcore Zelda fan like myself should try (other than masochistically getting a CD-i).
So, yeah, anyway, Four Swords Adventures needs more recognition, so I'm very excited for this. Again, everyone should find four GBAs and this game!