Halo3: I'm guessing 8.5 million and 9.5 million at most.

SSBB: Is a game for the hardcore but appeals to the casual gamers as well. With a very low learning curve due to the easy and fun controlls. Add in a free platform mode that appeals to the larger platform public. This game doesn't need a hype to sell well. This game is hyping itself! The online mode will take this game beyond SMG sales. And I expect SMG to sell atleast 10 million. You do the math.

I have a confession to make. I never owned Halo, Halo 2, Smash Bros., or Smash Bros. Melee. I didn't have an XBox or a GameCube (or a PS2). But I have a Wii, and I'm buying the hell out of Brawl, and I'll be creating levels on it and playing online with my friends for the rest of my life. We're not all casuals, and even casuals are interested in this game! The Wii stole a lot of hardcore gamers from other markets too, sucking us in with its magical control schemes. I was a StarCraft addict for years until I saw the first Revolution commercial. Now I gobble up Wii games like Reese's Pieces.

Halo 3 is Halo 2 with a whole mess of polish. That's not a bad thing. Why ruin a great game?
However, Brawl is Melee with Snake, Sonic, a level editor, online play, etc. etc. etc., it has a billion things that Melee didn't have. We might as well say this is the fight between Halo 3 and Smash Bros. 9.

Casuals will like this game. Hardcores will like this game. Same with Halo. Halo is the king of casual games anyway.

@ twesterm,.... yeah I see USED Players Choice copies of Melee, going for more then their original retail price...( once or twice I've seen them at 25 pound whhich is $52)

wow, people are asking a lot out of a early 08 release. If has good enough legs to still chart by holidays, then it has a chance to pass Halo. Just as everyone underrated halo earlier they do now.

Galaxy or Wii Fit has a much better chance.

GO!! GRAN TURISMO 5.....lolol

OT:

I think SSBB will outsell halo 3

There's so many reasons as to why Halo 3 will most certainly outsell SSBB, it's almost funny that people are even arguing for Smash at all.
Firstly, Halo 3 has much broader appeal, especially amongst the 18-30 year old crowd (the ones with money). Smash brothers appeals more to the Nintendo audience, and the "hardcore" gamers. You're not gonna catch many frat boys playing Smash Bros on their Wii, folks.
In addition, while the Wii might be outselling the XBox in worldwide sales, it's not that far of a lead, and a big chunk of Wii owners are way too casual to even consider playing something like Smash. Just look at the weekly software sales! XBox games are consistently outselling the Wii by boatloads, and it doesn't even have the advantage of bundled game numbers (yet).
Halo 3 is still topping the charts with 200k on week 4, and it's going to continue strong through the holidays. Seeing as how Smash is debuting after the holiday rush, when mommy and daddy's pockets are drained from buying the kiddies their Christmas presents, I don't believe SSBB will break 500k in the first week WW. The hype is just not at the same level as Halo, it's simply incapable of producing it.
And considering that Halo 2 beat out SSBM by almost 2 million, I don't think this is even a contest, really.

I say it's possible, and hear me out.

If you say that Smash Bros isn't attractive to your hardcore players, you're totally wrong. I know it was the game that sold the entire system to me back in the gamecube era. I still play it now, and I can't think of a single game that is more competitive.

so far, we have Smash Bros Melee at around 6 million, and Halo 2 at around 8 million, but I think a couple things should be considered.

however, what people aren't considering is just how much Smash Bros Brawl is being improved over Melee. there are a LOT of new features that I think will bring in a LOT of new people. Basically, I see 99% of everyone who bought Smash Bros Melee will also be buying Smash bros Brawl, just on the idea that it's the next in the series and more of the same good fun.
Now here are some points that I think will bring in new people.

Online Play - this one is obvious, now you don't have to worry about having your buddies over, just pick a day and play no matter how far apart you are. Plus if you have a greater competitive thirst to fulfill, you just hop online and you're set for some fresh competition from around the world.

New characters - Sonic, Snake and Samus(zero suit) As superficial as if sounds, these characters are going to spark interest from the non nintendo crowd, which will bring in new players. I also listed samus in there cause I just know she's going to bring in a few on the sex appeal card. Just look at Ivy on Soul Calibur.

Level Creation - As has been said before, this pretty much makes the replay value of this game absolutely and completely infinite. It will sell strong and keep going strong, and it will be played constantly, new people will be dragged into it to play, and they will then get hooked and have to go and buy the game as well.

now I'm not saying it'll outsell Halo 3 right off the bat, or that it's going to completely dominate, but I see it happening down the road easily enough.

My prediction

Halo 3 11 million sold (the game is at 6 mill and its been out for a month)
SSBB 7 million sold

You think Halo 3 will outsell Halo 2 by 3 million but Brawl won't outsell Melee by at least that much? You crazy.