Absolutely nothing is known about his past, and as far as we know, he's just a deranged Delta Beheeyem.
As a Boss Battle
Erwin rides atop a Metagross which... we're not entirely sure if it's still alive on its own. He uses Protect to shield both of them while controlling the Metagross to shoot Hyper Beams at his opponents. His Protect can be broken by a perfect-accuracy Thunder, such as during a rainstorm or a magnetic storm. When he battled Eskay and Mezzo, this Thunder was supplied by three strange pillars.
He has a tendency to teleport random Pokemon, such as Golett from Insula Nui, in as distractions.
- Erwin and his Metagross are based on Erwin's namesake and mecha from Pac Man World 3.
- Erwin's weakness to Thunder is based on a glitch in Pokemon Diamond and Pearl in which a move with manually-perfected accuracy -- such as Thunder in a rainstorm -- has a chance of ignoring Protect.