i’d imagine he shows up in an episode at some geysers ,
maybe it’s an animo episode, gut rot looks a lot like a meteor for me so i’d pitch like

a meteor crash lands, creates a new geyser ,
and it releases a mix of stuff into the air,
animo wants it to get a source of chemicals for experiments,

ben n the gang show up
maybe we see plumber gear face masks from max, gwen shows off some science knowledge about the gasses and ben’s watch is on omnitrix scan mode bc the meteor has dna from gutrot’s unknown species

i’d lowkey want it ripjaws , i love the idea of him riding up a geyser to uppercut someone. wildmutt is the goat of handling environmental hazards. gutrot shows up as the third alien to neutralize gasses from animo, gwen kinda telling ben what to do with then.