Trick Room seemed to be the deciding factor. Because his team countered it, and his opponent didn't use an alternate strategy he was able to take advantage of how slow Amoongus is. It isn't cheap to use someone's strategy against them.
Badge Case [Time Badge] StrifeHart is my OTP. services performed at BSC: 2 Riley's Boyfriend on the Pokemon BW2 & X boards. W1 FC: 4170 0917 6393