I think in the rule 63 alternate universe Amy would be a giant like Jim was but still sweet as can be. A big ol teddy bear named Andy. dresses like a metal lumber jack.
John is still freakishly tall but still technically a guy and hasn’t changed much, he’s just trans there. (multiversal constant is John masc / male leaning)
Dave is Daisy, a cute short-stack build girl that keeps her hair short because she doesn’t like people touching it. Cats keep following her for unknown reasons. She does not own any cats, they seemingly just materialize from nowhere in her house. Owns an extensive knife collection right next to the boxes of vintage my little pony dolls that she repairs as a hobby.
John and Daisy have been secretly dating since late high school. Andy joins the relationship after John gets sucked into another dimension for a while causing everyone to think he’s dead. So when John got back Daisy and Andy are engaged, they all agree to be poly, then go out of state to get legally married as a trio.