Aye, stupid AI is nothing special with these guys. For another example of stupid AI in the Battle Facilities, in R/S Battle Tower, if a Pokemon has Explosion, it will almost ALWAYS use Explosion, even if the opponent's Pokemon wouldn't be damaged by it. I distinctly remember one battle in the Tower with a guy who had the 3 Regi's. I switched out to Gengar and they all used Explosion as their first move each.
Shit like that ended up making me get a streak of 273 in the R/S Tower.