Agreed that the burden would be on NRS to regulate it, and it would definitely pose more of a challenge than balancing tourney variations like we have now.
However I don't buy into the whole argument that the game is just going to become this huge, impossible to balance mess. That argument gets thrown around a lot and I was just trying to give an alternate perspective. It comes with more ways to balance SHOULD NRS feel the need to, which would help keep the game at least somewhat balanced while retaining the fun and variety of customs.
Even if customs are added to the the competitive side of the game Is NRS gonna change the interface of the game to allow ppl to make their customs at the character select screen? Bc if no then that is just a huge waste of time logistically for actual offline play. It would be mad annoying and stupid to watch someone go to the custom screen and change movesets on a loss, or to watch them take turns customizing characters before each set. It would also elongate the time for the tournament to be held and if you ever been to a tournament those things take quite a while to happen. Grassroots tournaments would have nightmares trying to run a 15 man bracket for it considering the massive time sink that would go into set-ups actually being used.
Also some characters actually already have their most optimal builds and that says a lot considering ppl are talking about allowing customs. That means for some characters nothing will change while others get the world. Like stated before even if slots were added and moves were buffed. It wouldn't do a lot considering some characters got everything they would need in their base kit. Like my favorite example imagine Liu Kang with 5 custom slots. This character is already good, and has alot going for him. Now lets say they make low fireball a base move so now that no longer requires a slot to be used.
Now his base kit is:
*high fireball
*low Fireball
*Flying Kick
*Bicycle Kick
Then lets make his custom set and we got 5 slots to work with so we are gonna get a bit crazy.
*Shaolin Vanish
*Kasari Slam
*Dragon Parry
*Energy Parry
*Shaolin Stance
Now with what is already possible Liu Kang has zoning, teleports, a projectile parry, a high and mid parry, a command throw, and a stance and stance cancel. Liu Kang would effectively turn into a grappler, zoner, and rushdown character in one variation.
Now lets look at someone like Scorpion lets say we give him air throw as a base move since it's a classic move like Liu's low fireball
Now his base kit is:
*teleport
*spear
*air-throw
But lets get crazy with these 5 slots we got now
*Misery blade
*Hell-port cancel
*Sin blade
Scorpion is now just reborn and burning specter combined, but why would I pick scorpion when Liu Kang not only does scorpion's mix way safer. His stagger is way better. He has 2 parries, and a command throw and he can teleport? What is my incentive to be Scorpion?
We can look at Jaqui too. Lets look at her base kit and say she can have Cybernetic Override
Now her base kit is
*Bionic dash
*Grease Kick
*Shrapnel Blast
*Up Shrapnel Blast
*Cybernetic Override
But once again we have 5 slots so we can get a little crazy with stuff so lets give her:
*Bionic Bounce
*Air Ground Pound
*Lethal Clinch
*Air Ground Pound
*Robo Grappler
Now Jaqui can be 1st round KO and upgraded. Now she can KB on throw breaks, dash punch, lethal clinch, Uppercut, and her 33 on counter hit she can jump around and mix you up, she can cancel her stings with no cost to meter, get big dmg on alot of hits, she can punish you severely if she breaks your throws, all the while still having some great buttons and pressure. Meanwhile you have Scorpion who only got one new KB and that comes from air-grab. He does't get unbreakable dmg. He doesn't get the ability to access his cancels or mobility without the expending meter out of the same resource, and he still needs meter to access that dmg bc outside of f3,4 scorpion has no natural launcher.
and this aint even me trying to downplay the variation bc him having all of that is stupid but it's not the oppression and total screen control that these characters would inflict. You have characters with 9f mids, great anti-airs, small hitboxes, stagger pressure, multiple game changing KB's, abilities that make some tools other characters have useless. Meanwhile you got others that are gonna get stronger no doubt, but why even bother using them when you can just pick the characters that do everything your character does and then some exponentially better? It'd be what T6 had with Bob and T7 had competitively with Leroy and no one enjoyed top 5 of evo being Bob vs Bob, and watching most games being Leroy vs Leroy.