I noticed a lot of people saying that some things must be kept secret until the game is released, and while I agree completely, if this doesn't happen the overall quality of the game will not be hindered (seeing they announced alot of Smash Bros Brawl before hand and it's still one of my favorites).
However, I've started playing fighting games and one thing I noticed is how every game just spoon feeds you all of the content. In Street Fighter, Street Fighter X Tekken, Ultimate Marvel VS Capcom 3, etc. you start the game with EVERYTHING unlocked. While this was cool at the start, I realized how much this affected the need to come back. In Smash Bros, I'd argue the funnest part was unlocking all of the characters and stages, and after that getting the trophies/stickers/music, but if there is nothing to get, there's nothing to look forward to and no reason to keep playing any story/mission based mode. Not only that, but if everything is thrown at you at once, you spend much less personal time with each character and rather just try everything once, which is the last way you should play a fighting game.
With that said, I believe hardly anything should be available at the get go, if anything less than Smash Bros gave you at the start but stillw ith the same ideas behind it. Whether or not they spell out what you must do to get the unlocks or if it's up to experimentation is up to them. I just feel that if I launch the game and have everything there, I will just kind of be like "oh..." and have no need to do the stories and extra modes.
Playstation All-Stars should have most stuff be unlockable.