Some context here, all this is hypothetical and I wanted to make them as strong as possible without going to impossible lengths.

1) Sukuna: He wins, managing to keep all his summons (assuming he kept a piece of them all alive in the shadows and they all are recovered to proper level) and he picks up all the available Cursed Tools, such as Kamutoke his original lightning cursed tool, Split Soul Katana, Nanami's Blunt sword giving, and Yuta's ring (I assumed it could be used years after his death so Sukuna can definitely take it but only use it for 5 mins and only as a Cursed Battery). He doesn't use the Merger and just throws it away cause he was never the type.

2) AFO: He wins and take One For All, and New Order and he keeps all his quirks and maintain Control over Shigaraki. Didn't give him all the quirks as I doubt he wanted all the quirks but more like wanted to maintain his hold over the world.

3) Meruem: Hardest one but I assume he wins his Battle with Netero and instead of dying from  Poison of Rose bomb he goes on to absorb all the Chimera Ants to become so strong to rule over humanity and chooses his human side, so everything they can do now he can do as well.

4) Muzan: Well I truly believe he would have killed all the  Demons after getting the cure for  Sunlight and absorbed them and taken control of their Blood Demon Art and even taken their memories for good measure gaining Moon Breathing and Thunder Breathing and See through World cause why not?

This is still a Hypothetical so if you some things might not be possible but we are having fun don't we.

What if the villains won and achieved their hypothetical strongest possible form, without wanks who would win?(JJK, Demon Slayer, MHA, HxH)