While thinking over various Quirks I got idea on creating the most powerful Quirk (how it works, how was created, etc.), and I came out with this:
One For All, All For One | All For All | All Might
How it Works
Basically allows to use any type of quirks (at the same time) that user know until he/she know how they works like in case of Creation, or if don't just copy it by touch like in All For One (but without the unpleasant side effects). Also allows to transfer Quirks to others through touch (All For One) and by energy projectiles. at the end allows for multiple increase power of possess Quirks (One For All)creating a user almost unkillable.
How was Created
During the battle against All For One at the moment when he was winning. All For One was trying to steal Quirk from non-canon character(NCC) (which had the ability to temporarily copy Quirks by touch) but NCC was faster and steal All For One Quirk first, leading to mutations of his Quirk, then he took One For All from Izuku Midoriya and ultimately led to creation of One For All, All For One.
In the face of possible boredom NCC use his new Quirk and gave Izuku an improved version of One For All that contained additionally faster regeneration quirk, enhanced senses quirk and increased bone endurance quirk. Give All Might One For All but without transferred options and temporary Super Regeneration and strengthened Quirks of Izuku's friends when NCC was attacked by them.