I really hope Chuck has a Heracoss. A Fighting-type gym leader and Elite Four member in the same game, and neither of them had a Heracross, despite it being one of only three fighting-types introduced in that generation. Chuck needs both a major boost and a Johto element to his team, and Heracross provides it. But apparently GameFreak/Nintendo are either complete morons or s**t-scared of change, so it probably won't happen.
Pryce needs a better team, but there weren't many Ice-types back then, and Will has stolen Jynx, and Silver (and perhaps Karen) have Sneasel. Perhaps Piloswine, Dewgong and Mamoswine? Powerful pokemon, but only three pokes at the 7th gym makes it acceptable. A Glaceon is also quite possible. Actually, Glaceon would suit him well, that's a good idea.
I'd love for Jasmine to have a Forretress or maybe a Skarmory alongside Steelix and Magne
ton, but again that seems unlikely (grr). The best we can hope for is that both the Magnemites evolved.
As for Clair... she's kinda screwed by having only four dragons to choose from - three being from the same evolutionary line, and already Lance's signature line. I guess we'll have to have two Dragonair, though she should NOT have three. Then there's her Kingdra. Maybe Gyrados? Again, used by Lance. Onix and Steelix and kinda draconic. But Bruno and Jasmine have them. Dunsparce sucks, but it's not used by anyone else, and could basically be a weak-ish support pokemon along with a Seadra, bringing her roster to a more respectable five. Still, I guess we'll still be forced to endure three Dragonair again....
The Elite Four are actually OK when it comes to rosters, it's just the levels that badly need boosting. Will should have Espeon instead of a second Xatu, and Slowking fits him better than Slowbro. Bruno's Onix should evolve. Scizor fits Koga much better than Forretress, he's very ninja. Karen needs to lose her Gengar, Snesel/Weavile could fill that role, and Murkrow should evolve. I'd say Lance should have something other than one of his Dragonites, but I can't really think of anything other than Kingdra, Clair's signature pokemon. Yanmega would be pretty cool I suppose, being a
dragon-fly, and evolving from a Johto pokemon (which none of Lance's team did before).
I won't even start naming Kanto's gym rosters, because they need serious work and I have to go now. I'm just gonna say that they all need full teams of six, and levels AT LEAST over level 50. Blue's Rhydon should either become a Rhyperior or Tyranitar, but otherwise he's alright. Everyone else's team needs a complete overhaul. Apparently Red's roster changes, but I'm not sure how. The four Kanto starters will stay for sure, and Snorlax was a beast, so he'll stay. Maybe Espeon will be switched for something more powerful, maybe a Tyranitar.
Silver - A final roster of Starter, Weavile, Magnezone, Gengar, Crobat and Alakazam is pretty good, but I'd rather switch Gengar and Alakazam for something else, as Gengar is already used by Morty and Karen, and Alakazam by Blue and Sabrina. Perhaps Espeon and Umbreon, or maybe Tyranitar is involved. (SOMEBODY needs to have Tyranitar!
)
Just my thoughts.