Theories on Munchlax
I found this update to be rather interesting for something of the 'eh, not too exciting' variety.
I'm sure that this new PKMN will move at a gait that's slightly faster than Mr. Saturn's was in Melee, and that Munchlax might actually speed up a little to go after an item when it spots one. I don't know if it can jump, and it doesn't look like it can. I can't say if it would let itself fall off of the stage by walking or not...it's a 50/50 chance from my perspective.
Since it seems to get larger as it eats, it might move slower after each feeding. Now, I'd also assume that it would last for maybe 15-30 seconds, and with each item it eats, its time left might go down a little, so that if it stumbled upon a bunch of items, it wouldn't last long. Dunno if grabbing an item at the same time it does will do anything special, as there weren't really item grapple struggles in the last games, but that could change here.
Perhaps hitting it hard enough could force the item back out, giving it back a little of its speed and time, or maybe just speed. That is, if hitting it works at all. Either way, it would likely just use minimal damage, if any, against players that get between it and the item it wants. As far as specific items it eats goes, it might become stronger or weaker depending on what body-altering item it eats, and might, every once in a while, spit back something it doesn't like, creating potentially dangerous projectile weapons from clobbering items that may be picked up if they land again.
If it eats a Smash Ball, it might do nothing at all, or it could evolve into a Snorlax with increased power and would likely go away instead of reverting after using its attack. And if it eats a PokéBall or an Asist Trophy, it might take whatever was in there with it when it vanishes or might let what was in there out to attack.
I actually think that Snorlax will return once more, because this creature, while of the same species, behaves a lot differantly from the way Snorlax did in the other games. Munchlax might just eat the items and walk around, but I have a feeling that some variety will be added. Of course, this is all speculation.
Now the Brawl site says "Any item it gets, it eats! It’s kind of hard to tell it to stop, though." They didn't say it was impossible, but if there'll be a way for the unleasher to maybe get it to turn away, it's tough to say what. Maybe the player's taunt would do the trick?