I'd probably be a collector, but I'd be more confident in battling since, in a realistic scenario, any Pokémon can succeed. There are no tiers in the anime and manga, only love and hard work.
Omega Ruby & Alpha Sapphire, the day Pokémon pulled a Dallas and jumped the shark.
I'd just be a trainer who doesn't really specialise in a type nor strong Pokemon. I'd basically have a bunch of my favourites from different regions with various types.
In all honesty, I wouldn't be too much like him, but I would probably remind myself as Ash. The thought of getting to travel the world with friends, meeting legendaries (if lucky because it'll be reality and extremely hard to meet them), and raising your own and new pokemon sounds amazing to me. As for competing in leagues? Not sure how I would be there.