As I said in the Shipping thread, Giovanni/Sabrina as my main Special pairing.
I was surprised hearing that line from Sabrina, comparing the boy trainers to someone "as charismatic as Giovanni" and I double took, but then I noticed that if you use the anime pasts (considering the manga does not touch the GLs' pasts at all), you got quite the pairing.
Issues:
Past: Giovanni was trained by his mother in his childhood and their relationship wasn't the most emotionally productive (called him a "brat boy") and thus forced to be in his roles and obligations he was to grow up to be: the Boss Rocket and the Viridian Gym Leader. Sabrina's childhood was constant training by her father and suppressing emotions (except in battle, if you've observed manga Rina in battle, you notice how emotional she is).
Plus being raised by opposite sex parents, no doubt issues with the respective genders.
Image: As the final Gym Leader with his reputation (in the manga), Giovanni no doubt has to update that image and can not lose (watch his shock with Red in their showdown as he loses) and can not step out of that role (of course this is dumped by future offerings) or lose everything that comes with it, the Gym Leader, the Rocket, which feds into his worth.
For Sabrina, she was forced to maintain that constant emotionless pitch to restrain her psychic powers as she aged, with the bonus of a feared image as the Saffron City Gym Leader became into the picture and her deadened emotional image had to be broadcasted to instill fear into her opponents (granted, that's more anime but still carried over with Green's initial reaction of her).
Bond: Of the triad, Sabrina said she had Giovanni's ear of things to the twerps as she was going to tell him of her victory and their torture (as she was blasting them with the fused Legendary birds), and the Boss Rocket himself didn't care for Koga or Surge that much, but didn't have any issues with the Psychic Rocket. Best to say nothing than negative, eh?
At the end of the day, both are deeply mature and take themselves and their roles quite seriously. This with Giovanni and his virile image, (She's defensive of her body, as with Green's breast jab) and the mind games Giovanni presents himself with, (his mental clock) courtesy of his cerebral and analytical side (one reason why the manga Giovanni is a true character rather than the arrogant anime one), must have quite the temptation to become the inducement for her to cast out and find a relationship despite the roadblocks of her training and past.
All that cold intellect in match with the expert of the mind that is Sabrina, their passions spilling out in the battlefield (he showed his emotions and himself in the showdown against Red), and lastly, the similarities the two share could make into quite the relationship.
And all canon, a true pity it wasn't explored as she sounds the only one who Giovanni could truly be with (I can't find anyone with him in a true sense). All that possibility from two-four lines of dialogue. But then I always go for the underground pairing and the most sensible (yet most unlikely).
I'm funny and open minded that way.