Ezreal
Starting off our list, we have Ezreal, a top ADC choice. Known for being one of the safest picks in the game, his E ability functions similarly to the Flash summoner ability but with a lower cooldown.
All this makes him an ideal partner in a lane with Yuumi, where giving the enemy team an advantage is often necessary. Ezreal's E ability is also crucial for avoiding deaths as much as possible
Ezreal's synergy with Yuumi stems from his status as a hyper-scaling champion with high survivability. This pairs well with Yuumi's adaptive force damage bonus.
Additionally, Ezreal's Q ability is an ideal poke tool to complement Yuumi, effective both in lane and in later stages of the game.
As far as ADC champions go, Ezreal is the weakest early game champion in the game. With how annoying LoL champions these two are, you are waging mental warfare on the enemy, at the same time.
Sivir
Sivir paired with Yuumi becomes a formidable combination. While Sivir may not be the best scaling champion like other ADCs that synergize well with Yuumi, she compensates with the best wave clear in League of Legends.
This ability significantly counters the passivity often seen in Yuumi lanes. Moreover, Sivir's full lethality build, combined with Yuumi’s adaptive force damage buffs, turns her poke into a destructive force. Additionally, Sivir's E ability, a spell shield, effectively negates CC.
Sivir stands out as the only ADC that maintains map pressure in a Yuumi lane. She is arguably the best early-game ADC for Yuumi, allowing for aggressive plays like contesting drakes with your jungler.
I think that all this can be easily achieved by poking enemies out of the bot lane and forcing them to retreat, thereby gaining a tactical advantage.
Vayne
From my experience, Vayne and Yuumi combo faces significant challenges during the early game, more so than many others. Vayne's initial lack of damage, coupled with the necessity of skilled kiting to survive, raises the skill requirement considerably.
However, the speed boost and healing from Yuumi's E greatly facilitate Vayne’s kiting, making both laning and team fights safer.
In the late game, Vayne paired with Yuumi becomes incredibly powerful. Vayne’s passive, which allows her every third auto-attack to deal bonus true damage, enables her to efficiently take down even the strongest tank champions in LoL.
This power, combined with the ability to build Shieldbow for increased survivability and Yuumi's healing and adaptive damage buff, makes any late-game scenario with this duo almost a guaranteed victory
Twitch
Twitch and Yuumi's synergy revolves around using invisibility differently compared to Vayne and Yuumi.
While Vayne uses invisibility defensively, Twitch uses it offensively, catching enemies by surprise. This is enhanced as Yuumi becomes invisible when attached to an invisible champion.
The first back in the game represents a significant power spike for a Twitch Yuumi lane, allowing them to return to lane invisibly and potentially gank their own lane. Subsequently, each time they go invisible, they exert influence over the game from the bot lane.
Their disappearance often leads the enemy team to spam missing pings, causing them to either over-commit or become cautious of a potential gank. Furthermore, Yuumi's speed boost makes Twitch unexpectedly fast across the map.
Zeri
Alright, next up we have a Zeri + Yumi combo, which demonstrates a remarkable ability in team fights. Unlike Twitch, who relies on a well-placed ultimate and Yuumi's buffs to be effective, Zeri excels in hunting down and outlasting enemies to be the last champion standing.
Add to that that her best build is a tank one, and you have all the necessary things to make an OP champion God-like, as Yuumi thrives with a champion that exhibits one of these characteristics, much less all of them.
Miss Fortune
I know what you’re thinking. However, while there are other champions that would, usually, be a better pair for Yuumi than Miss Fortune, there is one thing you may not be aware of. And no, it's not just because she is one of the hottest LoL champions out there.
The combination of Miss Fortune and Yuumi's ultimates, along with the adaptive force damage buff that increases Miss Fortune's attack damage, creates a formidable force. Miss Fortune’s ultimate, which scales with lethality, transforms any team fight into a devastating bullet storm, leaving no enemy champions standing.
Moreover, Fortune's W ability is sufficient for harassment and safe farming during the laning phase, but it's in team fights where this duo truly excels.