Flamethrower > Water Pulse > Flamethrower
If Registeel would use a damaging Steel combo and you have at least 16 HP and you do not have a substitute, use Substitute (15) and push back.
If Registeel is under the effect of a p/e move when you would act, use Substitute (15) on the first instance and Moonlight on the second, restarting the queue each time.
If Registeel would use Thunder Wave and you are not behind a substitute, use Magic Coat the first instance and Substitute (20) the second.
If Registeel would use a damaging Steel combo and you have at least 16 HP and you do not have a substitute, use Substitute (15) and push back.
If Registeel is under the effect of a p/e move when you would act, use Substitute (15) on the first instance and Moonlight on the second, restarting the queue each time.
If Registeel would use Thunder Wave and you are not behind a substitute, use Magic Coat the first instance and Substitute (20) the second.