I am back from vacation There are some really good answers here and some new members too which are very welcome. :)
1. Yes I have. When I was young my favourite Kanto Gym was Celadon's. I liked how serene and peaceful it looked and the sheer number of trainers was impressive particularly as Erika is a relatively early Gym Leaders.
Whilst not normally a fan of the Cut trees. I like the addition here as it adds to the natural feel of Erika's Gym. I did not notice however that the Gym was in the shape of the female sign until it was pointed out by Ddrox.
2. In the games the Gym Leaders are given little to no character on the whole but Erika having an All Female Gym gave a sense of uniqueness to her Gym. This is even more pronounced in Gen 1 where the Protagonist had to be Male.
The All Female trainers also relate to the Pokemon in the Gym itself including the Flower like Vileplume family. Whilst there are numerous Masculine Grass Types now (Such as Chesnaught and Shiftry) other than maybe Victreebell this was not the case in Gen 1.
Female trainers have a tendency to dislike bugs in the games (And indeed Misty in the anime). This is shown quite starkly by the Paras line being nowhere to be seen in the Kanto Game Celadon Gym where all other Grass Type Families make an appearance. Indeed one trainer in the Gym implies that bug types are not welcome.
3. Not much to say here other than how he got in in the first place in what was a game primarily targeted to children. They had no choice but to change it in later games.
4. It is not too many trainers. For some reason the 4th Gyms occasionally have a lot of trainers. (Flannery has a seeming army in ORAS). Having seven Gym Trainers shows that Erika has the trainers as a circle of friends.
For me the trainer classes fit in with the Gym Character. The Beauty class (Whose Gen 1 Overworld sprites inexplicably have headbands) fit in with the natural beauty of the Gym and Erika's statement that she will only use Pokemon she finds attractive.
Lasses and Picnickers fit in with the Gym too and there is even a Cool Trainer (Now called Ace Trainer) in the Gym. This may well be the first trainer of that class the player faces and they even heal their Pokemon. The presence of an Ace Trainer may show Erika is respected among Kanto trainers.
5. I was aware of this glitch during my Grass Monotype where Erika's Pokemon seemingly threw the match by using Poison Powder over and over on my Gloom. As stated by Ddrox the glitch did not just apply to Erika and this was fixed in the remakes.
6. Erika's RB team - Victreebell - There may have been a glitch in your favour but there were also several oversights here. Victreebell had Wrap which could trap you permanently if you were unlucky, Sleep Powder which had the unfortunate habit of putting you to Sleep, when you wake up - That's your turn and to sleep you go again. And Razor Leaf which had a much higher Critical Hit ratio than it does today.
Tangela - The weak link in Erika's team. Constrict and Bind could be more annoying than anything.
Vileplume - Petal Dance is not the Powerful move it is now and whilst no pushover Victreebell is the true Ace of Erika's team here.
Yellow Team - A clone of her anime side. Whilst having Gloom and Weepinbell may have made it fair for Ash Ketchum who runs with unevolved Pokemon more than the average trainer, it doesn't work for me in game and for me they should have stuck to her RB team.
Much as I'd like to say Lilligant, the Flowering Pokemon is simply not available in many games so cannot really be my go to Pokemon.
My current Signature Pokémon is
Vileplume. Vileplume was the Ace of my Kanto Grass Monotype team AND my Johto Grass Monotype team and helped me win many battles particularly with Sludge Bomb in Heart Gold. Getting lucky with a Modest nature helped too.
It also learns my favourite Grass-type move Petal Dance. In short Vileplume is a Pokémon that has always served me well.
Welcome to the Club. I have given you a Budew as your first Pokemon for the Scenario Campaign. :)
I had no idea Snivy could learn Iron Tail by breeding. Might need to try that.
Welcome to the Club. I have given you a Budew. Let me know if you want a different Pokemon instead.
Wait, u mean a Budew gif? Or something else?
Erika is indeed very elegant as is her Gym in a way.
I will leave the Celadon Gym topic open for a little longer in case anyone else wishes to answer.