Baby's First Hack (Trainer Edits)

[Stacts]

Good morning,

Only recently started messing with GBA roms, specifically FireRed.  I'm trying to piece together a hack for personal enjoyment, and one of the things I want to do is add re-match teams to trainers which don't have them.  I know how to create new trainers and how to edit extant trainers.  I haven't learning decomp yet, I'm still using tools like AdvanceMap and a trainer editor, but using those tools, I can insert new trainers and they work (and some basic scripts).  I don't know how to associate trainer-data with a trainer as a rematch team.

So, that's my question: How do I add rematch teams to extant trainers such that the Vs Seeker will proc them appropriately? 

[mods, if this is in the wrong section, please move it]