So we already have a standalone DLC fighter (Pirahna Plant) and it seems increasingly likely we'll see another in future. But what about standalone stage DLC? Are there any games/franchises that would be popular enough to warrant standalone stages with music?
I think most people only really care about fighters so it's an interesting dynamic to think about. Are there places or games people would love to fight on rather than characters they'd want to fight as? Are there settings with fanbases rivaling BK or K. Rool that people would want to see updated?
I would prefer stage DLCs over Mii hats/costumes DLCs.
There are many locations I'd like to see a stage based on...
-Bowser's Castle
-Super Mario Land 2 island
-Clock Town
-Taltal Mountain
-Rhythm Heaven stage
-Kirby 64 stage (Ripple Star castle, pyramid, factory...)
-the Dreamstalk from Kirby Triple Deluxe
-A Sonic stage (Chemical Plant, Hydrocity, Radical Highway, Pumpkin Hill, Pyramid Cave/Sandopolis, Death Egg, Space Colony Ark, Tropical Resort, Aquarium Park, Metropolis-Forces, Special Stage, Studiopolis, Angel Island/jungle or emerald altar, Casinopolis, Scrap Brain, Rooftop Run, and many other super iconic places that would be awesome in Smash)
etc...
Actually, stand alone stages as DLCs would be awesome.
-The Neutral B/Up+B/Down+B/Side+B formula. Why do all characters have to be restricted to just this simple formula of pressing a direction + special button to do a move? Seems some characters should be able to do more. I don't propose making this that different, but instead I'd give characters unique inputs for certain moves that only they would be able to do. For example, Kirby has a move in Kirby Super Star where inputting down, then up+attack with the Yoyo ability causes him to do a tricky top spin that sends him up and down in the air. I'd give Kirby this move, and others similar moves where appropriate, so they're not always limited to having only four special moves.
-Analog movement/"Tiptoeing". Why is it there? It doesn't seem to serve any purpose. During a normal match it's rare to see players making really tiny microadjustments with just pushing their stick a little to the left. Pressing the stick all the way left or right seems to immediately send you into a run anyways without even considering the analog movement and completely disregarding the double tap to run feature. I would just make it so that the movement is entirely digital, and also velocity/momentum based, so that characters can both accelerate and slow down with weight and velocity like in Mario or Sonic. Your speed would carry over into jumps and you'd be able to access new moves, like running jump aerials. It would play closer to a real platformer in this sense while still being obviously Smash.
-Enhanced specials. This borrows a bit from SF, but essentially what this does is make Cloud's limit break a universal mechanic. All characters would have a little meter under their portraits with two segments to it - whenever they have a full segment, they can perform an enhanced special move by pressing A+B+Direction (this would also get rid of the "easy smash attack" input that uses that same input, sorry). These specials would draw on all the benefits of the custom moves from Smash 4, for example DK's enhanced down+B would be his "hot slap" custom move where he causes these little flame pillars to come out. His enhanced side+B wouldn't be a headbutt at all, but instead he pulls out a barrel and plonks it down in front of him, and anyone within the sweetspot would be captured within the barrel which he can then attack with a fully charged punch or however he sees fit, unless they break free. If he doesn't capture the enemy he still leaves a barrel in front of him for him to use as a thrown item or a shield against projectiles.
-Underwater combat. The swimming mechanic seems to serve no purpose and only a few stages use it. I'd make it so that underwater stages could be possible and provide an interesting new flavor of combat where you can swim through the water, but still get spiked and be sent flying as normal. Swimming would operate how it does in Mario Bros, where pressing the jump button causes your character to paddle and ascend, but doing nothing causes them to descend. There could be stages that only temporarily go underwater and stages that are permanently underwater.
I agree with you that Smash needs some innovation in the core gameplay because it's getting stale, and I would even accept huge cuts (along with no new characters, included my most wanted) as long as the gameplay is improved/revamped.
-About specials, I like the idea of giving more depth to the input of the specials, but I don't like having character specific input combos. In fact, I prefer the Dream Land/Adventure gameplay of Kirby over the Superstar-inspired one because I prefer a simple, intuitive and standardized input structure over having to read 3 pages of tutorial in order to learn all the hidden moves of the Fighter ability (just an example). In fact, I think that Kirby Amazing Mirror was a good middle ground where some abilities had a decent amount of different moves but they were all simple to activate and didn't need reading the pause screen. Back to Smash, I like how the movesets are standard, you learn the basic controls and you can pick up any character without big problems; so I wouldn't change that. Though, I would definitely add some more uses of the special button, like Inkling uses it to charge the ink while shielding. Using the special button during grabs to charge a bigger punch sound like a fun idea and doesn't require cryptic character-specific combinations of keys (simple or not); it would just incentivate experimenting with the special button during different status (shielding, charging, grabbing/grabbed, on ledge, etc). It's just a button, easy, intuitive, that's ok IMO.
-I agree about analog movements, and I would add that jump should be changed too: instead of having 2 jumps (low jump and high jump), have a jump that can be adjusted depending on the amount of time you hold the button. Still speaking of Kirby, Kirby Fighters is a smash-inspired game that uses this type of jump, and it has never been a problem for nobody, so I suppose it would work just fine. It would make the fight less about timing and more about positioning, giving more freedom to the player and adding a layer of variables that would allow for more mind tricks and variety in the strategy. I would also gladly accept momentum-based physics, both for basic movements and knockback (instead of having fixed angles for each move/hitbox, let the knockback react dynamically depending on the vectors applied to the character's body). This way the physics would become way more complex, but it would add a big amount of additional depth to the game... depth that simulates real world physics, so depth accessible to everyone, because if a gameplay element is natural, you don't need to learn it, you already know it from your experience in real world.
-I'm not a big fan of enhanced specials with a meter a la Street Fighter, but as I said before, I like the idea of adding more interaction with the special button during different status (such as charging a punch while grabbing only for Donkey Kong that was mentioned earlier in the thread).
-Underwater combat is a good idea, but I wouldn't do it like in Super Mario Bros... it would be very frustrating to wait your character to slowly descend... Brawl was criticized for being floaty, and underwater combat like this would be like regular fighting with infinite jumps and a super floaty environment. I'd rather let the characters swim up and down by pressing up and down, (once again to continue the parallel with Kirby) just like swimming in Kirby games. Underwater moveset should be more limited, but depending on the character, some should have more mobility and more moves. I'm not usre it would be a good idea to make full-underwater stages, because some characters are supposed to not be able to swim, or get damaged by water, so it wouldn't make sense to force them underwater. Also, if characters have big differences in their underwater skills, it would be a hell to balance, and each character should be balanced twice, once for regular game and once for the underwater gameplay. Having some underwater sections in some stage is totally fine IMO.
Stuff that I would add:
-Terry's stage has the wall mechanics. I would add something like this to every stage, this way you can't cheap KO people at the side of Mushroom Kingdom II with some grabbing move or stuff like that, unless the opponent is 100% or over. It would also be cool if more game elements were based on the 100% mechanics, similar to how the Great Cave Offensive stage can kill you with lava only over 100%. More stage elements should interact differently with characters who are over 100% IMO (maybe buildings that break only if you are thrown into them at 100%+), and this would also finally give a real meaning to the percentage.
-Parry: I would completely remove all the counter attacks from characters who have a counter attack (unless is some very iconic move of a specific character), and replace it with the parry mechanics that would be accessible for every character. Parry would activate by releasing the shield in the exact moment an opponent is hitting you with a physical attack (no projectiles) or during an attempt to grab you. Parry wouldn't automatically start an attack for you, it would just stun the opponent for a fraction of second to give you a chance to attack and eventually start a combo.
-Charging neutral moves: Not every move, but a decent amount of neutral moves should be able to charge depending of the time you hold the attack button, like Smash moves. The attacks that can be charged would start on release instead of on press, and become more powerful (but slower) the more you hold them. Charged neutrals would still be pretty fast anyway, the amount of charge possible would be minimal, still a fraction of second (if you charge for more than the maximum time, the attack would release automatically), just to give the player the option to fight DPS or damage dealing but slower. For some specific characters, even unconventional moves such as dash attack or throws could be charged.
There is probably more but this is all what came to mind for now.