Guildo could be a serious problem for the Avengers. His time-stop might only be good for running away, but he can bind multiple people who are much stronger than him and leave them sitting ducks for Ginyu or Frieza to destroy.
Frieza also has a lot of moves beyond throwing punches and energy beams. He can telechenetically throw mountains and has that bubble he traps people in that explodes on instinct with anything.