So, since discussion has died off, and I'm sitting at home bored, I want to propose an idea I've had for what I would do if I was developing SSB4 to keep things fresh whilst not messing with the previous gameplay too much. It involves the assist trophies. At the moment, do they really serve any great new purpose? Gameplay-wise, they're essentially Pokemon, and, although I know they were meant to 'fill the void' of characters that couldn't be put in as playable, do they really work? Was anybody that wanted Samurai Goroh as a character really satisfied by seeing him randomly spawn once out of every 20 times you got a particular item?
My solution: Have an 'assist' attack, assigned to probably the Y or X button by default.
Basically, after selecting your character, you'd be brought to a second screen full of assist characters (which could present a more obscure, 'out-there' selection than the regular roster), and each player would select one. Each player would then have an assist bar displayed on the bottom of the screen, which would build up through the match (you could change the way it fills in the settings, but by default, it would probably build up in a manner not unlike the score in the score mode in Melee built up, encouraging using different moves, etc), and, once full, you could use your assist. This would, in most cases, see your character 'become' your assist instantaneously, use its attack, and see you transform back into your selected fighter.
Each assist would have its own ability, and some would be able to do some more out their things.
The majority would use 'attacks' as normal. Fill meter, hit Y, change into character, perform attack, meter resets to zero. These attacks would be stronger than 'normal' attacks, and generally be good smash attacks. Some attacks could just be ripped from other characters but with a strength boost, for example Roy could be brought back, using his old 'B' attack (a great way to bring him back without using a playable character slot he probably doesn't 'deserve'), while others could be 'new' attacks.
Others may have less strong attacks, but get multiple uses. For example, you build the meter, hit Y, and you'll use the first attack, and lose whatever percentage of the mater necessary (so if you get 3 shots, you lose a third each time, etc). Your meter wouldn't build back up until you used all of them though, so you're encouraged not to hold on to them for too long. An example could be Duck Hunt Dog, who fires a NES zapper (similar to Fox's B, but stronger). You get 3 shots.
These could work for other types of 'attacks', too, such as recovery. I could picture a horizontally moving recovery move through Tails, and a vertically moving recovery through Balloon Fighter.
You could also go further than that, they wouldn't all just need to be 'attacks'. You could have a whole set of assist that just give the player an item / the effects of an item. A Lip assist could grant you an automatic Lip's Stick, activate Otacon, and its like you got a free Cloaking Device, activate Happy Mask Salesman and boom, 'free' Bunny Hood, etcetera. They would all act exactly as the items usually do, last as long, in some cases, can be knocked out of your hand, etc. Just a 'free' item.
You could even play with other effects. What about the various Djinns from Golden Sun giving you a limited time Fire / Ice / whatever effect to all your attacks? A Gardevour that uses protect to make your shield twice as big for a limited time? Maybe the pitcher from Nintendo's old baseball game could boost the power of all your projectile attacks.
Hell, get really weird. What about a Mr Mime that, for a limited time, replaces your character with a Substitute, which can be attacked for damage but won't go anywhere. Maybe the old idea of Ditto transforming into a character in the match could be brought back as an assist, I don't know.
Ideally, the system would add variety - if everybody is going to use Metaknight, at least have them using Metaknight with different assists - and also boost characters in certain ways to make them more viable - give a character with a tether recovery move a more 'traditional' one and they might be more usable for some.
I realise that it probably wouldn't be too long before the community realised that character X with assist Y was the best combo and went straight to a broken tier, but hopefully an assist would be easier to rebalance through a patch than a regular character, and, if not, ah well, the game would be broken to those players anyway, at least it gives more options.
So, that went forever, but there you go. Any thoughts?