Soundly beaten (8)
(Other definitions for thrashed that I've seen before include "Beat violently" , "severely punished" , "Beat soundly" , "given whitewashing" , "Beaten soundly" .)
(Other definitions for trounced that I've seen before include "Not cured after receiving heavy beating" , "Beat hollow" , "Thrashed, beat heavily" , "Defeated decisively" .)