AvengerG 20

This can definitely be difficult since there aren't many battles where you're facing more than 3 opponents, and you might be attempting this while also going for "No Child Left Behind."

My suggestion is to either go for this against wild dogs after the game is over, or just make a save, get the achievement without worrying about voiding the NCLB acheivement, then reload your save once you have it. 2 of Kenny's abilities instantly kill him if you fail them, so you can always use both characters to wear all 3 enemies down to very low health, fail Kenny's unicorn ability (sorry, drawing a blank on the name), and then use a New Kid attack that will finish them all off.