I know that you meant Bowser's castle as a full stage. That's actually what I really wanted to have too. But we can't have Sonic in the game unless maybe Sega permanently stays with Nintendo. Even then it might not work because isn't the game just about old and new Nintendo games? And Link was in SCII because he's part of Nintendo (correct me if I'm missing something here). Both Sonic and MegaMan would rock but how on earth could we insert them in Smash?
More ideas: internet tournaments (duh), Dr. Mario as just a costume instead of a character (I stole that idea so whoever first said it can kill me), and best of all... team mode!! In this mode you have two characters to control at once, but you just start out with one. When you start to get clobbered just push a certain button or combination of buttons and you will switch to your other partner with 0% damage! (to be fair the damage would stay the same for the characters when you switched back). This would also be a fun co-op mode!
Woah, look at the date! I need a new signature!
On November 21st, Nintendo will unleash the greatest handheld system on America that this world has ever seen. Two screens, two extra buttons, one touch-sensitive screen, wireless multiplayer, voice recognition, a rechargeable battery, and more. Prepare to severely wet yourself.