While we can't really call this duo villainous, they're definitely not a force for good in Faerie Land; they're really just a force for annoying. One of the few (intentionally) comedic characters in the poem, Braggadochio and his squire Trompart embody the inverse of the ideals of knighthood, mistakenly believing that the external, superficial qualities of a knight (his armor, sword, etc.) are what matters.
Nope, as we learn from all our heroes, knighthood is much more about who you are as a person than what you wear. Braggadochio's pride, cowardice, and impolite behavior with the ladies make him thoroughly non-knight material. His squire, Trompart, who has learned he can manipulate Braggadochio just by flattering him, shows how little power Braggadochio really has.