Congratulating rhymes with:
accumulating, annihilating, articulating, assimilating, calculating, circulating, coagulating, deregulating, emulating, encapsulating, escalating, extrapolating, formulating, immolating, innoculating, insulating, isolating, manipulating, mutilating, oscillating, percolating, populating, recalculating, regulating, simulating, speculating, stimulating, stipulating, tabulating, titillating, undulating, vacillating, ventilating