Hydro's rhymes with:
ambrose, bellrose, ciros, farrow's, guinarou's, gyros, hasbro's, melrose, microprose, montrose, overthrows, penrose, pharos, primrose, rockrose, tomorrow's, tomorrows, yoshihiro's
Hydro's sounds like:
haters, hatrick, hatteras, headdress, headdresses, headers, headrick, headwaters, heaters, heather's, heathers, heathrow's, hedrich, hedrick, heidrich, heidrick, heterosis, heterozygous, hetrick, hettrick, hitters, hooters, hydras, hydrick, hydrous, hydrox, hydroxy