It seems like nobody has tested this yet; Gotta try it out tomorrow.
I’ll be interested to hear your results. Having high defense and 11 resistances should give Registeel good staying power. However, there’s two things that have made me wary about investing in Registeel for Rocket battles.
Although Lock-On has incredible EPT, its damage output is more or less non-existent, so you’re basically 100% reliant on charge move damage to get the job done. That coupled with Registeel’s abysmally low attack stat could be a big liability, as you’re unlikely to one-shot anything (even when damage is SE) requiring another full cycle for a 2nd charge attack.
Since Rocket leaders use shields, I assume you’d need to lead with something else to bait out said shields before sending in Registeel. Trying to bait shields with Flash Cannon doesn’t sound ideal, especially with your quick move dealing almost no damage in between charge moves.
Tried this on a regular grunt and it works.
And don’t worry I’m only using Machamp, Melmetal or Giratina Altered to bait shields.
Registeel is only to clear out Tyranitar, Houndoom (No Fire Fang) or Gardevoir etc if I wish.