Premise
Naruto had just sealed Kaguya, with Sasukes help.
Kaguya somehow sends Naruto away to the MHA world.
As soon as he is dropped into the world he automatically transforms into his giant fox form.
Naruto notices the heros (even though he doesn't now that's what they are) having trouble with one person.
Naruto tries to help by grabbing All For One, only for All For One to try and steal a quirk (that he doesn't have) from him.
Due to this connection Naruto has Kurama take all of All For One's quirks including AFO.
After that Kurama holds all of the quirks in Naruto's mindscape for safe keeping.
The rest is up to whoever adopts this story. I just thought it up and I've never read a story like it.
You can make it Naruto x Harem or not it's up to you.