Or search: vouch, qualify, specify, guarantee, stipulate, undertake
3 Syllables: SUU
violating
4 Syllables: SUUU
calculating, circulating, correlating, desolating, emulating, formulating, insulating, isolating, oscillating, regulating, simulating, speculating, stimulating, undulating, vacillating
4 Syllables: USUU
annihilating
5 Syllables: USUUU
accumulating, articulating, assimilating, congratulating, gesticulating, manipulating

Found 23 words across 4 groupings.