Or search: polo, alien, comer, flier, flyer, mover, rider, rover, toter, bather, bearer, footer, mortal, musher, rafter
2 Syllables: SU
bachelor, bachelor's, traveler
3 Syllables: SUU
amateur, caliber, flatterer, gatherer, janitor, Latimer, manager, massacre, travellers, vascular
4 Syllables: USUU
ambassador, coadjutor, diameter, examiner, parameter
6 Syllables: UUUSUU
cardiovascular

Found 19 words across 4 groupings. Skipped 11 excess words of a similar stem.