Well...what CAN we expect from the AI? Can we expect Pursuit? Status? SDs/CMs/etc.?
You CAN expect Hax and unfair play, along with movesets . You have to do everything you can to limit the amount of destruction that the AI can cause with Hax. Substitutes, for example, will bring all of those OHKO abusers to a sudden halt. What better to counter something that is taking advantage of Water Pulse's seemingly 60% Confusion rate than Slowbro w/ Own Tempo? From the AI, you should carefully determine what moves the opponent is using, and then switch in something that can deal with the opponent effectively.
As for movesets, certain moves will indicate the presence of others. For example, if a Wailord enters battle and uses Whirlpool, you can expect to be in for something like this;
564 | Wailord | Impish | Chesto Berry | Whirlpool | Toxic | Amnesia | Rest | HP/Def/SpD
A toxistaller Wailord. IIRC, a similar thing exists with Clamperl.
Similarly, moves like Hypnosis will be accompanied with moves like Dream Eater;
585 | Exeggutor | Modest | Lum Berry | Dream Eater | Hypnosis | Leech Seed | Ingrain | HP/SpA
Incidentally, Leech Seed, which appears in this set, may be accompanied by Hypnosis, Toxic, Substitute, etc.
By spotting these "indicator" moves, you can detect with some accuracy what set your opponent is running, and bring in something to stop it from working before they have a chance.