His ability to regenerate adds a LOT to the fight! And, of course, that his primary attack ignores defense and has no ineffective types (except psycho, but those won't even survive the weakened damage). Man, that guy is the ultimate killing machine!
I think on level 100 he does something like 380 damage (Psychic does as much damage as you have Special stat points), only a select few even survive the initial blow. No matter, the second blow is always enough.