>>15301428He couldn't use a Kingdra because they go out of their way to give every significant trainer a signature pokemon others don't use, and Kingdra is Clair's.
Half of the things you listed have nothing to do with dragons (Scizor? Steelix? Kangaskhan?) - everything Lance uses bar Aerodactyl at least *looks* like a dragon. Sure, there's no excuse for not having Tyranitar in Gen 2 to fill the empty slot he had in Gen 1, but that's the only real thing you can hold against him.
And the reason he doesn't use Dragonair in Gen 2 is that his Dragonair in Gen 1 evolved into his Gen 2 team. That's why his team is identical to his Gen 1 team, but for the addition of a Charizard.