Actually Coalescence works fairly well. Heal anyone caught in the AoE while using the extra speed to remain outside of it, and maybe chip away at his health if you can line the beam up properly. I’ve even held him off with Rally (and Inspire, and had a Lucio backing me up), or at least stalled him a lot. Transcendence can work, but you really need to make sure to put Orb of Chaos on him first and then convince your team to gang up on him, or else you’re just going to extend his ult.
Amplification Matrix is a no-brainer, but as with Transcendence, you have to convince your team to use it. It’s actually easier to get people to use Kitsune Rush, making it perhaps a better solution. You can use it to burn down Ramattra or use it to exfil everyone quickly. Either or.
And then there’s Nanoboost, which works great if you put it on your tank, nade him, and send him in to challenge Ramattra directly.
And those are just the ult v. ult matchups. Sleep DOES work so long as Kiriko doesn’t cleanse it and your team is smart enough not to bring him around. If they aren’t then that would explain a lot. Bait out the suzu with nade, then land sleep dart and back out.