Please do NOT buff Yuumi
If Yuumi gets buffs she will probably be perma banned once more people learn to play her and stop turbo inting on her. The champ is ridiculously strong when played properly with little counterplay to Q harass other than hoping to run out of range of it in time.
I think a lot of her bad winrate is people being literally never leaving their ADC to get their auto shield off and not baiting out skill shots with her w. Like, her passive shield is disgustingly strong. She just makes laning hard with having only 1 body to attack, needing to focus the ADC while other ardent champs you can dive/kill them first. I know as a support main myself, I generally focus the ardent supports first, then the ADC unless the ADC can not be ignored or is out of position, but I can not do that with this champ.
Please riot for the love of baby Jesus do not buff this champ and let people learn her first for like a month, then decide.
I'd say the strongest counter I found so far is
and just hard diving the ADC
One character Yuumi is extremely strong against is
who literally can't get his double bounces without minions and even then yuumi can w to her ADC when brand ult is coming to her and make it disappear if she plays it right...all the while in lane can can harass hard and shield/heal her ADC through the brand poke.
; if she gets caged (like when she goes to proc Passive) it's game over for her
isn't even that good on her;
, however.....