Zeri

Zeri needs sustain and poke, and to not worry about her support, and yuumi gives her exactly that. However Zeri herself isnt the best adc so while yuumi is her best support, zeri isnt her best adc

Twitch

she can go invisible with twitch, so they have a lot of roaming and ganking potencial. However try not to Q when you are invisible since you'll reveal him

Caitlyn

It'll be hard to hit the Qs with her due to her attack range. This is an AP yuumi so we need to hit them, otherwise its not a bad duo

Jhin

Same as Caitlyn but he doesnt almost take advantage of our healing passive nor our attack speed boost

Xayah

Seraphine

She doesnt need more AP damage

Tristana

Tristana can lose kills easily by enemies flashes or heals, so a Q oneshot would help. also she is very squishy so she'll need that shield

Jinx

insane attack speed, insane damage, and you also slow them a lot just in case. This is not even about AP yuumi, this duo is broken

Ashe

Same as Zeri

Draven

League of draven

Ezreal

there are few supports who can follow ezreal in trades, so what about a limpet cat