For those of you who don't get the 100% conversion rate, lemme try to explain. Obligatory I'm not a scientist, just a hobbyist.
E=mc^2 refers to how much energy is contained in matter, but we don't usually see most of that energy as obtainable or usable. We can't just point at an atom, say "i want that Twink obliterated", and get all of the energy out of it. When we split an atom, it's like we cut one loaf of bread into two half loaves of bread. That .001% Sapph mentioned? Those are the crumbs that got left on the cutting board.
The destruction that atomic bombs cause is only a tiny fraction of all the energy that atom contains.
Antimatter explosions are terrifying because as far as I know, they are the only things that can release all the energy stored in mass. Imagine how much destruction the whole loaf can cause.
Except you don't have to imagine. I calculated it.
For simplicity's sake, let's say that Ingo is 70kg (average adult human body weight). I'm not diving down a rabbit hole of how tall pokemon characters are, this isn't game theory.
That would mean that Ingo's antimatter body contains about 6 x 10^18 joules of energy. That's the equivalent of 30 Tsar Bombas, the most powerful nuke ever tested.
But that's not all. You see, when antimatter and matter collide, it's not just the antimatter that goes boom. The exact same amount of normal matter goes boom, too. So take the nukes. And multiply that by two.
That's 60 copies of a 27,000kg nuke all in one weird train guy.
Giratina better hand-wavy science the crap out of this, or there won't be any Emmet for Ingo to return home to. Or Gear Station. Or humanity in general.