i was playing PWT at White 2 and battling against red's Pokemon in triple battle. I shocked that blastoise move 1st before my jolteon. i'm sure that blastoise did not use priority move and can use different moves.
Red's Blastoise in the PWT has a Choice Scarf, which raises the speed of the holder. Assuming his Blastoise also had some EVs in Speed, this explains why it moved before Jolteon (especially if your Jolteon doesn't have max speed). I hope this helps!
In BW2, Red's Blastoise holds a choice scarf. This increases Blastoise's speed to around 213, which is enough to outspeed something as fast as Jolteon.