The greatest hero of the MHA-verse takes on the Berserker class version of Heracles from the Fate-series.
No time limit for All Might. He gets all his feats from the Vigilante manga and the Two Heroes movie in addition to the stuff he's done in the regular series (they don't really contradict anything he's already done anyway).
Berserker gets all his feats from the visual novel, Grand Order game and the various anime adaptations of the story. Assume he has a top tier master giving him the mana required.
No ring outs.
If it's too one-sided in All Might favor we'll give him the three hour time limit he had at the start of the series.