Yeah Viridi wasn't solely characterised as tsundere. It was a small aspect of her character that didn't have much focus until near the end.
She was a favourite though. She was trying to do the right thing but went about it the wrong way. She had everyone against her, but Pit was understanding of her, Palutena too. She's still effectively a child though so she didn't know how to respond, so she lashed out at people instead, thinking she was more powerful than everyone else, that she could take care of herself. It was less tsundere and more just her being a bit childish.
The tsundere stuff didn't come until around the end, with the PitxViridi teasing. However, she is friendlier overall at that point in the game anyway.