What you need is to let one of the brutes with the stun rod hit you with an attack that will knock you down, while 2 or more brutes are close by. He will put his foot on your back, while the others jump in. i got it three times in a row, by letting him knock me down. The regular brutes don't seem to be able to knock you down, so look for the ones with the stun rods.

 

Just fast-tap whatever button it asks to fill the bar, Hulk will knock them all off and unlock the achievement.