If you could add additional features (Non-character DLC)

[Deleted member]

I would add the old Classic mode, i'm not too fond of the Wii U's classic mode.
Oh, and alternate costumes.

 

[RaenUE]

Hmmm....
The ability to import/create custom Robin and Villager. Body type for Robin would be out, since it'd change height and/or weight, but I'd take a different face and voice any day. Maybe the ability to create patterns for villager's clothes/umbrella.
A stage that is literally Coliseum for Wii U but with no walkoff.
More options with custom stages (eg. ability to create stage transitions [like Delfino/Skyloft], rotating platform configurations [Like Pokemon Stadium/Arena Ferox], and semi-random stages [like Tortimer Island], maybe more hazard options).
More freedom with the controls; eg. more remapping options for 3DS (read: let me change the second jump to something else), the ability to disable/enable/create button combos (eg. Shield+Attack=Grab, Attack+Special=Smash), the ability to create a blank button that is used as a shortcut for button combos a la 'control' on computer keyboards, a button that can toggle between control configurations (c-stick for smash => c-stick for tilt), etc.
More alternate costumes (not colors), like the Kisekae costumes, would always be welcome.
If we ignore the time it would take, I'd probably also want an adventure mode like Melee/Subspace Emissary.
A mode where everyone gets a set of a given number of random fighters and have to fight it out (like the end of smash tour sans stats) would be neato.
The ability to spectate and auto-rotate out players when a five or more 3DSs connect locally
Tournament mode would be nice if it would actually arrive
Backwards compatibility for replays

That list was certainly longer than I thought it would be.

 

[Smash Arena]

Adventure Mode would be a cool DLC feature, done in Melee's style with all the Smash 4 characters. Giga Bowser returning as a boss? Yes please. Also, additional events would be wonderful and probably very easy to make. Events seem to be scripted matches or battles with different victory/loss conditions, so I'd imagine they would require little to no new code. I would pay $5 for 20 additional events.

 

[Ravioko]

A few people have said this already, but a pallet editor/creator. Like in Street Fighter X Tekken, but with less micro transactions. I mean I'd sorta' get being charged a few cents if it's, like, special reflective textures or something, but other then that, free.

 

[asia_catdog_blue]

Did someone already say "All-Star versus?" Because, I would like that.

Also, some Character Variations; ala, "Mortal Kombat X."

Variation A: Sword & Shield
Link relies on the Master Sword & Hylian Shield for offense and defense

Variation B: Magical Rod
Link uses the Magical Rod for Fire & Ice damage.

Extra Items & Sub-Weapons can be Custom Moves.

 

[Weedy Spyze]

How awesome would it be if you could import your Villagers custom outfit from an Animal Crossing game to play as in Smash Bros 4? Even if you couldn't 'share' your costume with others in online matches it would be fantastic if I could see my Smash 4 villager dressed as my New Leaf villager.

Was actually thinking of this the other day, and I agree it would be a very neat addition. At the very least, Villager could use more alts. He deserves 16 more than Little Mac did.

The game is already adding so many characters but what it really needs are stages.

So true. I mean there aren't too fewer stages than characters (47 vs. 50) but it seems like there are so many fewer stages that are interesting enough to fight on. Most of the retro ones are from Brawl, and I'm honestly kind of tired of seeing most of those options. They should've taken the Mario Kart option and have about an equal amount between Brawl and Melee, and I guess a few from 64.

Anyway, to add some more things off the top of my head:
1. I agree about alt costumes. Shirtless Little Mac tops my personal list.
2. A more in-depth stage builder, definitely. They could at least add some Nintendo-themed backgrounds rather than the 5 generic ones we have. I tried downloading some retro stage recreations but I couldn't keep them in my game because the backgrounds usually threw me off.
3. Speaking of stages, bring over Gerudo Valley, Magicant and Mute City from the 3DS version. Perhaps put Jungle Hijinx or some other fitting stage to that version for the trade-off.
4. An option to put our own music into the game would be nice.
5. I'd like a Melee-style Adventure Mode, but not at the expense of other features. Smash is all about the fighters/multiplayer than anything else. No thanks to any Subspace Emissary in Smash ever again.

 

[EnigmaticKnight]

I would add Break the Target, Board the Platform, Boss Battles, Adventure Mode in some kind of shape or form, and the original Classic Mode from 64 or Melee.

 

[IndigoSSB]

More than anything I'd like a way to share custom made stages. The idea of a custom color pallete has been thrown around, I have to say I like that idea as well.

 

[CrazyPerson]

HAZARD SWITCH. Turns off stage hazards, thus greatly expanding the list of viable existing stages. (Stadium 2, Kongo Jungle without the barrel cannon, Pyrosphere, Mushroom Kingdom U, Gamer, Garden of Hope, Wily's Castle, and Norfair all become viable for tourneys. Maybe even Luigi's mansion or wrecking crew...).

Hazard switch is something that is long overdo... quite frankly this should be patched in free of charge IMO.

 

[CrazyPerson]

Subspace Emissary 2

I respectfully disagree... Subspace was a terrible direction for smash to go.

If they made a game around the concept of a bunch of Nintendo characters in a side scroller and built it from the ground up to bet hat I'd probably buy it... but smash bros mechanics didn't fit into this at all imo.

 

[n8han11]

As with everyone else, I wouldn't be averse to another Subspace Emissary. But I would like it completely redone, as I felt that Brawl's Subspace Emissary was rather bland, and due to everyone remaining silent, they couldn't interact with each other to the extent they should have. If Smash 4 has a Subspace Emissary, They should have it in the style of the Smash 4 character trailers, with elements of Smash Run and Smash Tour thrown in.

 

[Ivander]

3DS:
Custom Music for Smash Run that you can choose from your SD card.
Options for Smash Run, including how much time it lasts, how much Smash matches last and which Final Battle happens at the end of the game.
Race to the Finish for Classic Mode.

Wii U:
A Mode that allows you to fight the Bosses without Event Matches or other Hazards.
More objects to choose for Stage Builder, including falling blocks, ice, moving treads, stairs and Danger Zones from Great Cave Offensive.
More space for Stage Builder and more backgrounds, including the backgrounds from all Omega stages.
Be able to make 8-player stages for Stage Builder.

Both:
More Alternate costumes that are either true costumes or palette swaps that make sense and/or a Palette Editor for characters.
More stages.
More music.
Make some of the Non-DLC outfits from each Mii Fighter be able to be used for all 3 fighters like the Suit from Gunner.
Make a special Mii Fighter character for all 3 classes for Non-For Friend Online, based on the ones from the Official Art and with their own Alternates.