Inspired by another post, if the Old Guardians of the Globe knew about Viltrumites, which ones could they possibly take on and defeat? I think one of the contributing factors to why they lost against Nolan was because they were teammates and they were shocked. So, with prep time or awareness, who could they take out?
They could probably beat any of them except the two I mentioned ONLY if green ghost was able to incapacitate them. Otherwise, I still think any viltrumite could beat them except >!Oliver!< until he was about Marks age