Formation rhymes with:
deformation, malformation, deformation, malformation, deformation, malformation, sarmatian, acclamation, acclimation, affirmation, amalgamation, animation, approximation, automation, confirmation, consummation, cremation, dalmatian, defamation, deformation, disinformation, estimation, exclamation, exhumation, inflammation, information, intimation, malformation, misinformation, proclamation, reaffirmation, reclamation, reconfirmation, reformation, sarmatian, summation, transformation, unimation
Formation sounds like:
fermentation, fernandina, ferrandino, ferrentino, fiorentino, framatome, frantom