Wutan Her, or one of the drunkard team, Cape Jasmine I guess? But Iris suffer lots from her bad raw stat.
Gardenia is not that weak - she has +20% skill chance and +15% attack to everyone- huge ability to 5* as compensation to useless third ability. And her skill is not x2, like for example QotN's but x2.1, and she is so cute. She may be not the strongest, but definitely not one of the weakest. I was even thinking about the drunkard team on Nutaku - Heather, Hop and Gardenia, but i don't have Gardenia there yet.