Satomine Night
The Power of Z!
Dragonite is a Dragon/Flying type, so it doesn't have a resistance to Electric types. And the Orange League wasn't a tournament with many trainers competing, so it wasn't a traditional League.
A league is a league, regardless of whether it's a major or minor league, or a traditional or non-traditional league. The Orange League might not have been a traditional league, but it was still a league, and so it should still count. Ash defeated Drake and became Champion of the Orange League, with the trophy to prove it. And so what if Dragonite doesn't have a resistance to Electric types? It was still a tough opponent, and it's still a pseudo-Legendary.