Iron Hands just has really good stats and typing. It's really bulky, and slow, which is actually fine for raids. In Terra Raids you just attack whenever you click a move, being slow means you have more stats in places other than Speed - like Attack. Speaking of, it's a Fighting type, which means it hits a lot of things with STAB, it has Quark Drive, which can boost your Attack even more with a Booster Energy or Electric Terrain, and it has Belly Drum for setup. Once you do that, max attack Drain Punch is just instant recovery. If you can tank one or two hits, which you can with an Iron Hands, you can get off a Belly Drum, and every subsequent Drain Punch will heal you all the way back up to full health.
