The Wiki says on the Bugsite page:
Bugs are classified by maker (FE, Sting, Ruger, Tahiro, and Jank), which partially determines their weaknesses / resistances to attacks from other makers.
and
Moves are classified both by maker and damage type (Blade, Strike, Special, Fire, Ice, Wind, Electric, and Ground). Each Bug has its own list of weaknesses and resistances to different damage types, which can be checked in its stats.
And I’m not in a position to play the ROM patch at the moment so; does this mean each maker has 1 or more weakness or resistance and the other one(s) are randomized per bug (not ‘species’ of bug, but individual)?