Algus Underdunk
Smash Journeyman
I do think that disc-to-disc communication via WiFi would be a clever way to keep characters locked away.You know, now that I think about it, I thought it was suspicious that Mewtwo and Roy weren't a Pokeball/Assist Trophy respectively...
This is unlikely, but not impossible in the slightest. Sure, maybe the Wii's internal memory couldn't hold two more characters for the Japanese players (which is so incredibly doubtful it couldn't), but you know what? An SD card could easily do it (not many don't have one now anyway)!
Nintendo making people buy additional stuff to play a game? That sounds EXACTLY like something they'd do (Link cable, E-Reader, GBA-to-GCN cord, CLASSIC CONTROLLER, etc)!
Keep in mind that later versions of the game in Japan could easily already include Mewtwo and Roy.
...also, the Mewtwo + Roy addition to US copies of Brawl would serve to explain why the delay between releases became so much larger than before...
...And you know, with the whole ability to give Wario two alternate outfits, I'm actually a bit sad that Mario isn't able to at least don the Doctor outfit, even if he wouldn't fling pills anymore...
But, c'est la game.