>>51147309This is what I'd go with for the Kanto Gym Leaders, although I prefer to stick to the generation, I am tempted by a few gym leaders to throw in the odd Gen II Pokemon like Marill for Misty, Lanturn for Surge, Jumpluff for Erika, Crobat for Koga, Espeon for Sabrina, Magcargo for Blaine and Donphan for Giovanni.
Mainly though I went with Pokemon that I think fit each Gym Leader's character, Brock's kinda hard to work with but given the other Rock-Types are fossils (aside from Rhyhorn) I figure it's better to just leave his team as is since I don't really see Brock as a fossil expert like say Roark. Misty I gave Seel since Lapras was a bit too strong and I don't think Goldeen fits her that well, there was also Psyduck I guess.
With Surge I always like to give him fully organic teams (i.e. no machine Pokemon) plus Electabuzz is prevalent on his team in other generations. For Erika I swapped Victreebel for Ivysaur since I think Ivysaur fits her better, more so because Victreebel comes off as a very deceptive and aggressive Pokemon whereas the rest of Erika's teams tend to come off as more battle of attrition-like.
Koga's team's basically his three aces (Weezing, Venomoth & Crobat) plus Muk which is his most consistent Pokemon. Sabrina I gave Hypno and Jynx mainly for the whole mystic kind of psychic rather than slight of hand psychic like Mr. Mime and a character like Will has.
Blaine got Flareon cause between it, Ninetales and Charizard I think it fits him best although admittedly it's more of a team slot filler. Magmar was cause of his other iterations of his team. Giovanni I gave Marowak cause it makes more sense given Team Rocket's actions than Dugtrio and Golem as a sort of book-ends to Brock's Geodude.