My expectations:
Single Player:
Classic Mode- Bring back achievements, Character-specific Break the Targets, Board the Platform, Race to the Finish, and would it hurt to think of new challenges and unique fighting scenarios?
Event Mode- Please be more creative like Melee's event mode.
Adventure Mode- Melee's adventure mode, while short, was a very fun experience to replay. If they decide to expand on that concept that'd be great. If they decide to go down the SSE route, it would be great if they actually used worlds from the franchises instead of the generic wastelands.
Cut out the useless stuff like the demos.
Multiplayer:
-No excuses. Bring back all the stages and characters.
-More useful, creative items.
-Tripping must be optional
-Hit-stun must make a return so combos can exist.
-Faster paced and add weight to the characters.
-Perhaps to add more depth to those that like to play competitively or advanced at a casual level, bring back the light shield, add a lag cancel technique, and another movement technique ala wavedash.
Characters:
-The NES Icons: Simon Belmont, Ryu Hayabusa, Mega Man, Little Mac
-Others: Ridley, Rival Trainer (Blue/Gary or Giovanni), Travis Touchdown, Saki, Isaac.
Other:
-Limitless replays
-More stage parts
-More interesting Nintendo Trophies that give insight to Nintendo's history.
-Music. Please don't make 100 variants of the main theme. It drove me insane with Brawl. More original and orchestrated work or at least be more bold/creative with the remixes.