Battle Tower in Crystal, I lead off with Mewtwo while my opponent has an Exeggutor. I outspeed and Ice Beam the plant for 70% or so damage; he then retaliates with Psychic that does next to nothing. Great, I think, another Ice Beam and he's a goner. But! Somehow, he outspeeds me and Explodes on me, critting and killing my poor psionic mutant.
Frustrated, I run calcs for Exeggutor's speed. There was literally no way it could speed tie with my Mewtwo. Yet somehow he managed to get its death throes before I could kill it. I STILL can't wrap my head around that one.