This being in SSB4 General and all, I feel as if I should point out that Ace Trainer JOE! will be incorporating some features I'd like to see in the next installment to the Smash series, such as the universal removal of random tripping 
. Some moves will still cause tripping to create a sort of "prone" status to abuse, however.
SUPER SMASHES: :bbutton:+:abutton:
In Brawl, when you broke the smashball you lost the use of your Neutral Special since that then activated your Final Smash. This is alleviated in SSB4 by mapping it to the simultaneous B+A input as well as introducing the Super Smash, a powerful but limited special move, to be used when you do not have a Final Smash handy.
Super Smashes are generally limited by either Ammunition (noted by a counter next to the character portrait, showing how many Armor Pieces ZSS can throw before she's used up her Super Smash), a Timer (Mario's FLUDD Spray/Hover Super Smash can only be used when a bar under his character Portrait is full, with each use draining it only to refill with time), or when a Special Condition is met (such as when Olimar has 3 or more Flower Pikmin, allowing him to perform his "Pikmin Carry" Command-Grab), but a few Super Smashes here and there are a combination of the 3 mentioned here and often vary in power depending on the amount of Ammo (lower ammo = higher power, dont waste it!), Time to recharge (longer recharge, better power) and the Condition that needs to be met (the harder/more situational, the better the reward).
As for Ace Trainer JOE!, each of his Pokemon have a Team Combo as their Super Smash, that both requires Team1 and Team2 to be within a character length of each other to perform (Solo Pokemon lack a Super Smash), as well as usually a timer or other effect between uses. Each different pair has their own unique Super Smash, mix and match Pokemon to see all 15!
DYNAMIC AIR-DODGE:
A compromise between Brawl and Melee, you may only air-dodge once but do not go into special fall afterwards unless you press a direction with it. Pressing :rtrigger: without :stick5: input will do a Brawl Air Dodge, following your momentum. Pressing :rtrigger: and :stick6: on the other hand will do a Directional Air Dodge, which stops any momentum you had prior as you shift mid-air, but also means you have to try and DI back to safety while in special fall. Due to Directional Air Dodge returning, Wavedashing/Wavelanding also comes back via :xbutton:+:rtrigger:+:stick1:/:stick3: close to the ground, allowing for precise spacing while moving between platforms or simply while in combat on the ground. Remember, while only a few characters -really- benefit from Wavedashing, Wavelanding is a handy technique on most stages for proper spacing and evasion.
SMOOTH LANDING:
While most Aerial moves Auto-Cancel when you land with them, some come with landing lag that can range from mild heavily punishable. This is alleviated in Smash4 with the ability to Lag Cancel Aerials by pressing a :ltrigger:/:rtrigger: during the landing lag of a move. Depending on when you press the input, you can reduce the landing lag by 1/4th or even 1/2 the normal time! This makes heavier moves a bit less risky to perform close to the ground when you finally master the timing and spacing for the cancel, and faster moves a tad less overwhelming as it'll be much harder to get their 1/2 lag sweet-spot.
HIT-STUN CANCEL THRESHOLD:
In Brawl, you could cancel hit-stun very early by pretty much any action, where in Melee you couldn't really cancel it until the stun was over (and don't even mention 64's crazy hit-stun). Smash4 introduces a threshold to cancel hit-stun once you are hit hard enough to start leaving a smoke trail as you fly through the air, you can cancel the stun with any action. There is a bit of a catch, however: the harder you are hit/higher %, the harder it is to cancel the stun, acting like escaping a grab in some ways in how you have to mash the input you want to cancel with slightly to escape before it's too late. The new threshold both allows for offensive comboing to take place at low-mid% without it being easily interrupted as in Brawl, as well as survival to be a bit easier once flung off-stage at higher% (with skill) than it was in Melee. On the topic of survival, it should be mentioned that fall-speed in Smash4 is much like 64 in that it is between Melee and Brawl, allowing for a bit more air fighting than melee, but keeping a bit faster pace than Brawl.
UNIVERSAL Z-AIR:
No longer limited to those with tethers, every character has access to a Z/Grab move once airborne. While there are no "throws" from the air, some characters do have a special throw of sorts instead of an attack (Such as Lucario doing a Grab-Only Force Palm that meteors opponents downwards, or Captain Falcon doing his UpB Grapple Attack with 1/2 the damage and Knockback, and no explosion or added movement), others can transition their Z-Air directly into their standard grab by holding on and pummeling the opponent as they fall back to the ground (Such as Diddy's Zair where he pummels the foe like with Side B until they either escape or touch ground), and others merely have an attack like Link or Samus for theirs. Unlike Link or Samus, non-tether Z-Airs do not extend the range of which you can grab an edge. It's a nice addition for most characters, but then again a lot of their Aerials are more reliable to land and/or more rewarding than their Z-Air, but you can always find a use for it with practice!
