It's official. Pokemon Amie will kill competitive pokemon.
According to this http://www.serebii.net/xy/pokemonamie.shtml Pokemon Amie will introduce a number of completely random effects in-battle. As Pokemon simulators are all about replicating in-game mechanics in the most faithful way possible they can't selectively restric this new mechanic. At the same time competitive pokemon aims to ban randomness from battles, no matter how inconsequential it may be (*cough*Snow Cloak*cough*). Here's the interesting part:
The unique feature with Pokémon Amie is that after you have utilised the feature, you will come to see various effects in battle. These features range from superficial to largely beneficial for the trainer which allows for greater strategy in battle. Most of them occur randomly, with the rate currently unclear. The effects known are as follows
Text: The introduction message, and various statements throughout battle change in context Critical Hit Ratio: The ratio of Critical Hits is increased Evasion: The Pokémon's evasion is increased
The following may be attributed to Pokémon Amie based on the visual representation, but it still isn't clear
Paralysis: The Pokémon has a chance of healing itself from paralysis Survival: The Pokémon has a chance of enduring a hit which would have knocked it out