Considering the 3DS has a joystick, I can see a SSB3DS happening, since that would help with Smash attacks and leaves the D-pad for taunting or something else.
(If SSB3DS had a control scheme I created this is how I'd design it)
Control Stick: Shouldn't it be obvious? >_>
Start: Pause/Reset (with L+R+A)
Select (Hold): Hold and press a "+" direction to do a taunt
B: Special (lol)
A: Normal (lol)
Y: Jump
X: Jump (mostly because I'm not sure what else would be useful for it)
L:Shield/Roll
R:Grab/Drop or Throw Item
+:"C-Stick"/Camera Swap (See modes below)/Taunts (see above)
Home Button(online): Start texting
Screen (Modes switched by tapping the screen [tapping would be disabled while texting and would be enabled again after the text is sent], the change between modes would be instantaneous without fades so you could quickly "loop through" the modes to go back to the previous one:
-Texting mode (By clicking the home button while on wifi since the home button is disabled online, so might aswell give it a use by enabling a keyboard to come up on the touch screen
-Stat mode (Icons [lives, damage%, character icon, time, etc. are moved to the bottom of the screen to make the top screen unclutered.
-Closeup mode (Remember the screen on the Pokemon Stadium stage? Basically that's what the bottom screen would be for)
-Cinematic mode (Uses the sides of the + to focus on different characters, and the up and down on the + to use different angles)
-Map mode (basically fixed-camera mode view on the bottom screen with only icons)
(Plus usage for menus, etc.)
Of course we haven't heard of a SSB3DS, but you never know, maybe one of the developers will see this.
![Stick Out Tongue :p :p](/styles/default/xenforo/smilies/tongue.gif)