Okay so I got bored... so I decided to make an 'updated' team roster for the first three Gym Leaders - bearing in mind to keep them 'challenging' but not 'impossible' (might do the rest later...)
These are just purely my opinion, and was done out of boredom - so no harsh criticism please... (But your opinion is welcome!)
(Changes made in bold)
1. Julia
Helioptile, Magnemite, Voltorb, Emolga, Luxio, Electrode
Having 2 Voltorbs seemed slightly redundant (although I think this was done on purpose to ensure Julia makes use of the synergy caused by Explosion/Selfdestruct and her field effect) - so why not have a Magnemite? (It can also explode right?)
Blitzle never really caused much problems for me - so I replaced it with Luxio (although Flaaffy might have been suitable too)
2. Florinia
Maractus, Cacnea, Ferroseed, Grotle, Breloom, Cradily
I think her team is fine as it is - since its supposed to be a Grass-Sandstorm Team (too bad her starting Pokemon doesn't start a Sandstorm). I suppose Grotle could be replaced with Swadloon/Leavanny with Overcoat, but that seemed slightly harsh.
3. Corey
Arbok, Koffing, Croagunk, Trubbish/Garbodor, Skuntank, Crobat
...I might have gone slightly overboard with this one.
With 3 Poison-type experts in the game, it felt extremely redundant that all three trainers carried a Grimer (pre-E14) - and none of them had a Koffing or an Ekans.
I know Corey had a Trubbish in the past, but again - Cain and Aya doesn't have a Garbodor so why not?