A champion that isn't only sitting on the Pokemon League  and he is interested in making his region better.
		
		
	 
Replying late to this, but I don't agree at all that we haven't had those already.
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Lance proactively investigates Team Rocket in GSC and their remakes, before the player ever gets involved
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Steven and 
Wallace both, in their own way, are clearly interested in making their region better and in its wellbeing
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Cynthia doesn't stay tied to the League and travels throughout Sinnoh, and her research definitely seems like something which would make the region better, by understanding it more deeply
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Alder explicitly states that he is on a journey around Unova and gets involved with all kinds of people, encouraging new talent like Iris and the preschoolers he has you and Cheren battle
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Iris doesn't have any defined role outside of being Drayden's protegee, but she's younger than the others and openly questions what kind of champion she will be, so I think the point here is that she's not quite on the same level yet. Notably she doesn't take part in the PWT, which I think implies her relative inexperience compared to the others. But it's clear to me that she will eventually be a more accomplished figure in her own right
-who knows what 
Diantha does on a day-to-day basis, but she clearly isn't tied to the league
-this is 
Kukui's whole thing. His motive in creating a Pokemon League is improving Alola so it can stand alongside other regions
So really the only one who doesn't quite fit this is 
Blue, and he at least takes a job as the Viridian Gym Leader (even if he's not that committed to it) so it would seem that he feels at least some sense of obligation to his region.
Now, if you mean in terms of their job, that's something I could get behind. Blue and Lance were both very much just trainers with little other responsibility, but increasingly as the games have progressed we've seen more champions with a duality in their roles, having some sort of other interest besides being a trainer. Steven is a rock maniac, Wallace is a contest master, Cynthia is an archaeologist, and Diantha is an actress. But for the most part this is just flavour and doesn't really impact the story, and none of those occupations are public service-type jobs.
I've mentioned before about an archetype I'd like to see the games try out, which is a champion who is a politician of some kind. We see politicians occasionally in the games and the anime but they're usually ineffective bumblers or outright villains - I'd like to see a Champion who was a politician with good motives, and whose first priority was contributing to the development and improvement of their city/region. Much as politicians come and go, the champion could reflect that one day soon they'll be gone, with someone new taking their place. I won't expound on this too much as it probably veers into wishlisting but I think there's great scope for a champion who is explicitly a public servant first and a trainer second, with them reflecting on how the two roles come together.
By design, this sort of character - much like Alder and Leon - would likely be identified as the champion from the start instead of being a "secret champion" like the others.