Virgil had a lot of potential to be an interesting rival- all of the Eeveelutions, a charismatic personality, but...what else?
It's no secret that his main purpose was to promote the Eevees, but as a character, how do you think he faired?
I wish he had been given more screen time, because I feel like we didn't get a very good feel for him to care one way or the other if he did well in the league. He was introduced way too close to the league to develop much of any character besides "oh he has all of the Eeveelutions". I wish he had been given more back story - what made him want to train all of the Eevees? Why does he like Eevee so much, anyway? What's so special about all of them that makes him want to focus on that evolution chain rather than using different Pokemon? Nor were any of his battles all that memorable.
Even if he was there only for promotion purposes, there's still a lot more they could have done with him.