I've played against VI as Pantheon, It was a fair fight and both Champs are fairly strong. If your question is asking, what champ is a good match against Vi. Then my vote is on Pantheon! :)
I think Vi is more like a jungler with great ganking power. Doesn't really counter anything in my opinion, or maybe I just didn't notice/see good Vi players.
Since I'm not sure if you want to know what champions counter Vi or the other way around I'll just answer both as best as I can.
Counters to Vi: Essentially durable, high-armor champions who like to trade with their lane mates. Champs like Yorick, Jax, Riven, Irelia, and even Garen will do very well against Vi. Also Champs that out-burst Vi like Darius and Pantheon will do fairly well against Piltover's newest champion.
Champions Vi counters: Basically any champion who cannot withstand high burst damage will struggle against Vi. Vi does well against champions like Olaf (uses his HP to trade) and Cho' Gath (Can't fight if CC is dodged or ignored). Vi also does well against the often-banned tanks Malphite and Shen, both champions can withstand Vi's burst but cannot return enough damage back to pose any threat to the Piltover Punisher.
I hope I was able to help :)
* Also sadly Mr. Cuddowls is a little misguided as Teemo does very well agains Vi with his infamous blind + shroom + AA combo. If u want to counter Teemo personally I suggest Yorick or Gangplank.
Pantheon does okay against her I think. My first 2 games with her I got destroyed and both vs Pantheons. Maybe it was cause I was new with the champion but Pantheon normally does okay against AD Champions.
i mean.. its a true story bro.. D:
Counters to Vi are:
Vi is Strong Against:
Counters to Vi: Essentially durable, high-armor champions who like to trade with their lane mates. Champs like Yorick, Jax, Riven, Irelia, and even Garen will do very well against Vi. Also Champs that out-burst Vi like Darius and Pantheon will do fairly well against Piltover's newest champion.
Champions Vi counters: Basically any champion who cannot withstand high burst damage will struggle against Vi. Vi does well against champions like Olaf (uses his HP to trade) and Cho' Gath (Can't fight if CC is dodged or ignored). Vi also does well against the often-banned tanks Malphite and Shen, both champions can withstand Vi's burst but cannot return enough damage back to pose any threat to the Piltover Punisher.
I hope I was able to help :)
* Also sadly Mr. Cuddowls is a little misguided as Teemo does very well agains Vi with his infamous blind + shroom + AA combo. If u want to counter Teemo personally I suggest Yorick or Gangplank.