Mainstream rhymes with:
bloodstream, gulfstream, jetstream, midstream, sidestream, starstream, woodstream, bloodstream, gulfstream, jetstream, midstream, sidestream, starstream, woodstream
Mainstream sounds like:
masterman, mastrianni, mastriano, mastroianni, mcdearmon, mcdorman, mcdurman, mcternan, mctiernan, minestrone, mostrom, munsterman, mysterium