>>50759655There's a number of things we can infer from game information. Like for one, he's got good eyes. When you first meet him in Wedgehurst he mentions Hop's exact growth at just a glance.
"Look at you, Hop! I reckon you've grown...exactly an inch and a quarter since the last time I saw you!"
"Bingo! That's the sort of sharp eye that's kept you undefeated so long, eh Lee?"
Secondly, he's got a good body. Dude is not only looks beefy, but he's trained under Mustard, a martial arts master, and earned enough of his respect to get a shot at Urshifu (which he ultimately failed to get because lolbadatdirections). You could stretch this to say he's got a martial aura, or his physicality borders on the superhuman, if you're writing that kind of setting. Regardless, he's obviously at the peak of human ability.
Thirdly, there's his immense talent. Even as a dumb 10 year old starting his journey, Leon never lost, ever. He remained undefeated until he won the Galar Challenge on his *first try*, which is obviously impressive considering the number of participants, and the experience between them. He's got some serious MC bullshit going on behind that goofy smile and terrible fashion sense. Opal, the 80 year old veteran whose whole shtick is analyzing people, mentions she's never encountered a talent like Leon's in all her years. What exactly 'talent' refers to, I'm not sure. He sure doesn't look the scheming type, so it may be his instincts are just obscenely good, and he battles through intuition.
He's got no special bloodline, no particular wealth nor special advantage, but that only makes his rise to power more impressive. He was literally just some kid from nowhereville who thought to be the very best one day, and actually followed through with it. In many ways, he's a mirror to your typical game MC, which was a brilliant idea to implement in a Champion character. It's just a shame that, like most of Gen8 in general, GameFreak completely fumbled his potential.