Theories and such

The possible outcomes if AFO takes OFA

We know that OFA is killing its users if they have their own quirk, but this rule probably won't on AFO, thanks to the fact that his "cup" is technically "limitless", though it's not explained if AFO has some kind of drawback with a big amount of quirks. The only thing that we know - consciousness of quirks and their wish to return back?

Seeing that AFO already can use a lot of quirks, even when he is weakened and had only a copy (?) of his original quirk, he would quite easily handle the power that OFA has. The only bad thing for him would be the past users of OFA. Thanks to the fact that they can use their quirks in OFA space, it means that AFO would also be able to use his own. Also, seeing that he was living for a long time, their wish to push him out or even block OFA from AFO would be almost futile. AFO could try to find a way to destroy those afterimages of past users and be done with it, but can he find the way to do this or not - is unknown. OFA users would also try to restrain him from doing so, though its hard to say if AFO would feel it or not. He could also try to restrain them, just like how his copy of consciousness did with Tenko (though in this case it would be more successful, seeing that thanks to Tenko AFO had a chance to steal OFA, using his hate. Plus, as we have seen, Tenko himself have freed himself from AFO'S control. But, its still can be considered as a copy of consciousness, so, original AFO would have way more odds.).

The problem with OFA past users is solved (though maybe not ;-;).

Now, how exactly would OFA work for AFO?

As we know, OFA is a booster quirk.

It buffs your physical statistics and such things. Though it mostly does that with someone like Toshinori and Izuku, thanks to the fact that they are quirkless.

What exactly it does with quirks? The same thing what it does with your physical statistics - buffs them.

AFO has a lot of quirks, most of them are probably useless (though maybe he threw away the quirks that he got in his uprising era - the era when he gave his brother the stockpiling. Why would he throw away quirks from that era? They are useless. Straight up useless. Only thanks to quirk singularity theory, useful quirks started to appear). For an example, one of the useful quirks, the Air Canon.

This quirk has destructive capabilities and is pretty easy to charge up.

Add to this OFA.

Let's imagine that air canon could destroy a building or several buildings in a line for an example for... Idk, some city blocks in a row?

Adding to this OFA would not only increase it's destructive capabilities, but also maybe range. Plus, it's easy to use those 2 simultaneously and SPAM IT.

There are a lot of quirks that AFO has, really. For an example, his ultimate attack had a lot of strength enchantment quirks. Adding OFA to those would be way to destructive.

All might, not in his prime, with the last bits of OFA managed to perform a city buster attack. And AFO with OFA, would quite easily put this attack in a shadow. May I remind you, this is still a weakened AFO. You could say that AFO in his weakened state but with OFA would put even prime All might into embarrassment/shadow.

You could also say that AFO, along with dr. Garaki would try to either copy OFA, or at least make the stockpiling function work again. And again, thanks to dr. Garaki, he would live for a really long time. If needed, he would even find after some years a perfect healing quirk to put him back in shape OR he would find Eri. Thanks to those factors, and the fact that he can actually switch bodies, he is essentially immortal and in future also invincible (again, quirk singularity theory...).

He already has the quirk of ragdoll (? Or which one of pussy cats?) That lets him see information, how strong someone's quirk is and things. Along with OFA, that also buffs it's user senses and this quirk, he would sense when a powerful quirk has appeared and would "gladly help" the child by taking away this dangerous quirk. After a lot of time, he would also get a lot of copies of the ragdolls quirk, new searching quirks in the future and his arsenal would only grow.

But, that's just a "realistic" theory, would you believe it or not - your choice