Because she tried to use a bunch of weightlifting equipment as a focus to summon Saber (shown in Hollow Ataraxia IIRC), Tohsaka gets All Might in the Archer slot instead of Emiya. He appears in the state he was at the start of MHA, which is to say, still in possession of One For All, but still limited to three hours a day (although even Tohsaka probably can't meet the mana requirement to sustain it that long). Only feats from the original three stories (Stay Night, Unlimited Blade Works, and Heaven's Feel) apply for the Nasuverse characters. All Might will participate in the Grail War, at the very least because it endangers people the longer it goes on.
How do he and Tohsaka get along? How does the Grail War go?
While I can't recall any huge amazing speed feats in the original stories, if I'm missing some iteration that put everyone at bullet time or something, we'll just say that the Heroic Spirit template puts All Might into the ballpark of the other knight classes enough to make it a non-factor.