Flummoxed rhymes with:
affixed, akst, angst, anikst, annexed, axed, axt, bakst, baxt, betwixt, blixt, boxed, climaxed, coaxed, context, datext, faxed, fixed, flexed, hext, hoechst, hypertext, indexed, intermixed, kekst, maxed, mixed, mixte, next, nixed, outfoxed, overtaxed, perplexed, pretext, relaxed, sexed, sixed, subtext, taxed, teletext, text, transfixed, unmixed, untaxed, vexed, videotext, waxed, xeroxed
Flummoxed sounds like:
flanked, flimsiest, flinched, flunked