I'll focus on characters and stages in my post. I think the cut-off for inclusion in Brawl was the start of 2007 (just over a year before Brawl's release), meaning any game released in 2007 was not represented in Brawl; the most recent games referenced were iirc Pokemon Diamond/Pearl (September 2006) and Twilight Princess (November 2006). I personally think that SSB4 will release in the first half of 2014 and therefore I am predicting the release cut-off for conclusion will exclude any games not currently announced; ie we will probably recognise all the stages and characters included. That said, I would love to see:
Stages:
Dark Aether (Metroid Prime 2):
This stage will make use of the light crystals and poisonous atmosphere found in Metroid Prime 2. If players are outside the range of the light crystals, they will lose health due to the poison in the air. Some of the light crystals are permanent, others will last only a short time and can be re-activated by an attack.
A Super Mario Galaxy themed stage (Super Mario Galaxies 1 and/or 2):
This stage will have two or three planets, each with their own gravitational field. These will therefore essentially be three circular platforms. Maybe a black hole could also appear, acting as a hazard.
Wuhu Island (Wii Sports Resort, Mario Kart 7 and Pilotwings 3DS):
I would imagine this stage being similar in style to Brawl's Isle Defino stage. A moving platform taking the players to various locations around the island. These can include at least one from each of the above games.
Characters:
Shulk (Xenoblade Chronicles):
Most attacks are done using the Monado. Final Smash could be the cyclone monado talent arte, which damages other players in close proximity and topples them, pushing them to the ground and rendering them immobile for about 15 seconds.
Zael/Elza (The Last Story):
Most attacks will be using his sword, with maybe side special attack being a horizontal shot from his crossbow. Down special could potentially be his 'gale' skill, damaging other players and unequiping them of hold items. Final smash could be his 'accelerate' skill, making Zael/Elza considerably faster for a period of time.
Mii (Many Wii/3DS games):
Appearance based off the Mii associated with the profile one is playing on. Attacks will be from a variety of mii using games, such as baseball bats from Wii Sports. I'm not sure of a final smash, but one idea is having the stage swarm with other Mii's, but that's quite similar to Dedede's current Final smash.
