The problem I personally have with this idea is that it's unneccesarily complex.
For Ryu, the button system was a crucial part of representing Street Fighter properly.
The overcharge mechanic is not a part of Splatoon mechanics and thus doesn't need to be a part of Inkling's Smash mechanics.
On top of that, the Inklings would be unique through their ink mechanics themselves, so they don't need to resort to another over complicated gimmick
I don't see how "charge the attack for a more powerful weapon" is "unnecessarily complex." The overcharged specials are tied into the ink; you can only use them while you're on your own turf, so laying down ink is rewarded.
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IndigoSSB
Right off the bat, I appreciate how you decided not to make the standards a mess of different weapons, and instead used a single weapon for them. I used tentacle-based combat (i.e. slapping foes with the head tentacles) and attacks in squid form, but the inkbrush certainly fills that role too. With that said, I do have a couple of problems with how it's executed here. Firstly, it makes the Inkling feel like just another generic sword user. There's not much that the brush does that's different from a sword -- it doesn't even lay down ink or anything, except for forward smash which is just inkonsistent -- and literally all of the moves are copy-pasted from other sword users. Also, I feel that this makes the inkbrush take up the entire moveset when it really shouldn't. I mean, it's not even in the main game -- it's an add-on through DLC. Perhaps the smashes and some of the aerials could have used different weapons?
Now onto the specials. Splat Charger and Super Jump are rather harmless, other than the lack of the iconic Splatter Shot.
But why can the roller not be rolled? That's the entire purpose of the weapon.
Anyway, now for the ink mechanics themselves. Firstly, I don't think you needed to nerf them as much as you did -- or at least, not in the
way that you did. Yes, not everyone has an ink mechanic, but that never stopped Rosalina from having a Luma, or Robin from having limited resources, etc etc. Rather than instantly changing something, you should first ask, "How would the opponent combat this?"
Now, the way ink works in my moveset is like this: Most weapon attacks lay down ink (but not tentacle-based attacks and such). It comes in two varieties: thick and thin ink. A roller makes thick ink, for example, while the charger makes a thin trail. Thick ink is often harder or more time-consuming to place down. Opponents will get their feet stuck in ink and their movement is slowed down, and thick ink slows them down more than thin ink. The Inkling can swim through the ink at Captain Falcon's dashing speed, and even cancel the ending lag of attacks into a squid dive while they're on top of ink.
So, what's the catch? Firstly, the ink can be destroyed. It can be attacked by opponents, and thick ink is more durable than thin ink (although neither are especially durable; maybe like 10% at most). It'll also disappear after <10 seconds, so the Inkling will have to break briefly from the fighting in order to maintain its turf; however, skilled Inkling players will learn how to inktegrate ink-creating attacks into their combos and combat, blending the two together and showing a truly skilled Inkling player. The Inkling is a combo machine in its turf -- almost like Little Mac on the ground -- but out of ink, it's weakened quite a bit. What's more, getting hit out of a squid dive causes the Inkling to pop out of the ink and "whimper" for about a second -- like hitting a barrier at the top of a wall in Splatoon -- thus giving the opponent time to strike. Squid swimming is fast, but if someone does manage to catch an Inkling, then the punishment is rather devastating. What's more, it also adds a bit of strategy to squid lag canceling; rather than doing it every time like l-canceling, an Inkling may opt not to do it, to avoid the recoil caused by being hit out of a dive.
See what I mean? Rather than limiting the Inkling's ways of laying down and utilizing ink, first think of ways to combat the ink while still keeping to the core mechanics. In my moveset, that's accomplished by the ink disappearing over time, being destroyable, the punishment for being hit out of squid form, and the need for the Inkling to take time to maintain its turf. Rather than making Luma only be part of Rosalina's animations -- like how the duck and the dog are two characters, but don't separate -- they instead made Luma separate, but easy enough to get rid of, with a stamina meter, super-light weight, and inability to act out of a tumbling state. Instead of giving Robin a way to get his tomes back -- which would stray away from his "resource management" theme, since you don't have to manage them if you can restore them at will -- they instead made the tomes and levin sword powerful enough to justify them having limited uses. Don't stray away from the core mechanic unless A) it would make the character better to play as, or B) there's absolutely no way to balance the core mechanic as-is. In my opinion, neither of those are really true.