For my case, the AI have a lot of weird moves that their Pokemon have either runs out of PP very quick or it uses the wrong moves at the wrong time.
My funny moment is when I fought that crazy Doctor's Rotom, made him wasted all Ominous Wind' PP (But really though, that move ran out so quick that I personally find it the most useless pokemon on his team, he just kept spamming discharge till it was out of PP, discharge was second to be out of PP after Ominous Wind) then he had less than 4 confuse Ray left and many double team left and I had two ground pokemon (Flygon & Golem, hey I love Golem xD) laughing at his face while trying to hit him, who he had no chance (Rotom was also the last Pokemon I had to fight against... with no ground moves) as he kept spamming double team non-stop (I casually use some of super potions while switching my pokemon just for exp since he had no attack moves left after long boring fight)
Personally, I find Rotom useless all the time whenever I face against it.
That battle was stupid and Fern made it even stupider than others, his Serperior... still uses Growth with its Contrary. (I really don't think anyone will fell for its ability any more, he use growth, I eat him alive with poison)