One thing some people who've done a lot of research into the battle maison observed was that the four sets each Pokémon had increased in competency, going from gimmicky with the low set to highly tuned with the final, fourth set. suspect that's true of the battle tree as well, and what you're seeing. Lopunny1 does similar stuff in the maison since fake out overrides the AI's priorities, even though a human wouldn't run fling+toxic orb alongside fake out without klutz.
Also, while I'm aware wild pokemon don't usually count here due to their almost completely random move choice, I think the pelippers at the start of Poni Island deserve a mention- Swallow/Spit Up/Stockpile/Roost leads to a lot of wasted turns. I know there moveset is that way due to how wild Pokémon's movesets are determined, and not any conscious choice on the part of the developers, but still. The sheer incompetence of those pelippers is kind of hilarious.