Super Smash Brothers Brawl included one major addition that will please those who tire of endless AI matches, or just general fans of co-op: a more highly polished story mode, called Subspace Emissary. Two players can team up to travel through some dimensional portals, or alternate realities, or something similar to rescue a cosmic McGuffin or some such; really, like with Destroy All Monsters, the plot is largely irrelevant; it's all about mixing up the vast array of characters. Subspace Emissary plays more like a traditional side scroller, and features bosses from across many different game series, such as Rayquaza from Pokemon and Meta Ridley from Metroid.
Subspace Emissary could almost be a full game release of its own. It is a tad on the short side, but there are replay options aplenty. There's a great blend of steady progression and seemingly impossible challenges, along with a serious dose of fan service. The few problems with this mode are very minor, most notably the fact that the screen follows Player 1, and Player 2 can often get teleported into new places with little to no warning if Player 1 moves too far away. All in all, this is really no more than a nitpick, and Subspace Emissary is a fantastic co-op experience.
If you own a Wii, and enjoy local multiplayer gaming at all, you simply must get a copy of Super Smash Brothers Brawl. It is one of the more kid-friendly series around, yet is deep enough for a hardcore gamer to really sink his or her teeth into. The humongous roster of both all-stars and distantly remembered characters gives the game serious replay legs. If all this wasn't enough to convince you that Super Smash Brothers Brawl is a worthwhile game, let me put it to you this way: Mario and Kirby vs. Sonic and R.O.B. 'Nuff said!