Or search: pet, deary, ducky, lover, rival, dearie, darling, favored, macushla, contender, favourite, preferent, challenger, competitor
2 Syllables: SU
ablest, Amos, anus, Arab, baseless, baseness, basest, basis, bracelet, bravest, Buenos, Caius, Davis, famous, favorite, graceless, gracious, greatest, hatred, heinous, Janus, latest, makeup, patriot, plainest, plaintiff, sacred, safest, shapeless, spacious, status, tasteless, waitress
3 Syllables: SUU
favourite
3 Syllables: USU
Andreas, audacious, capacious, compatriots, contagious, courageous, fallacious, hiatus, Ignatius, loquacious, outrageous, sagacious, tenacious, ungracious, vexatious, vivacious, voracious
4 Syllables: USUU
dictatorship
4 Syllables: UUSU
advantageous, affidavit, Athanasius, efficacious, Himalayas, ostentatious
5 Syllables: UUUSU
disadvantageous, unostentatious

Found 60 words across 6 groupings. Skipped 4 excess words of a similar stem.