I just remembered that I hadn't bumped this topic to answer my own question of how Injustice 2 would be, after they revealed the details.
You can in fact choose new or altered special moves, however they can only be used together with the main Gear system, which means dealing with damage and health modifications too.
Obviously most fans of existing fighting games are resistant to stats and leveling up affecting their experience, so because Abilities are tied to the overall Gear system, their use is limited to a subset of modes, including single player and un-ranked online.
Which is a real shame, because several of the more interesting and fun looking special moves characters have are Abilities.
And similar to Smash, they are unlockables that you get at random.
Here's hoping Seth Killian returns with a new fighting game that really goes hard on the player moveset customization aspect, where it's a core gameplay feature that can't be avoided by change resistant fighting game traditionalists, and handles them in a way that's convenient for local play and live events.