Z:
Ogami's resurrection that revived Toji
Comedian
Angel's technique
S+:
Idle Transfiguration
Limitless. No explanation needed, but because it can only be used at full ability with 6-Eyes I feel the need to note that Neutral Infinity, which is what makes Gojo hardest to beat, probably doesn't need 6-Eyes to wield given that it seems to be the first stage of the ability.
S:
Hakari's technique. Would be in S+, but I think the ability benefits a lot from plot induced stupidity and isn't super useful when the user is outclassed. Uraume could've taken Hakari's head for example instead of an arm and Sukuna would have no problem dicing Hakari's head either.
Ranta's technique, which froze Maki a long while despite her power eclipsing his own. Only requirements seem to be looking at the opponent and maintaining a hand gesture? Strongest support ability I think and would probably get Sukuna killed if used on him. Stun + free brain stab from Yuta/Maki.
Cursed Speech. Similar to the above with a tradeoff of drastically shorter effects in exchange for a laxer requirement that allows it to be used more offensively.
Kirara's technique. Basically a shared neutral infinity unless the opponent knows some obscure trivia AND where every marked object is, which can change in a millisecond. There's a reason Kirara and Yui Yui poofed near Sukuna so casually.