I’m not aware, but do any of the cores have xbrz support?
PPSSPP might have xBRZ per-texture upscaling, but in general we use xBR shaders.
Note: there’s some outdated info on the interwebz talking about how xBRZ is better than the shader versions, but Hyllian, who developed xBR in the first place, has long since improved the shader versions such that those comparisons are no longer valid.
But senpai, everytime I try to use super xbr is looks like this: 
https://s13.postimg.org/46ovt3udz/retroarch_2016_11_18_18_08_43.png
Not so good.
Its the super xbr shader from the common shaders. The scanlines are from the overlay section.
Are you using a super-xbr preset or just trying to load the shader on its own? I ask because it looks like you’re using linear filtering and xBR requires nearest neighbor to work properly. The presets will set this for you automatically. Also, I think super-xBR is specialized for antialiased images(?), so try using one of the non-super xBRs. xBR-mlv4-multipass is very smooth and relatively fast.
You might also check out Sp00ky Fox’s ScaleFx 9x shaders for cartoony games like Mario Kart.
Ok, had to choose from within presets instead as you said. Now it looks right. Thx. I chose scalefx 9x because in the mario kart logo, the M in Mario Kart looks pretty much like a str8 vector line. While in scalenx and xbrmlv4 multipass, it’s a bit of a wobbly line (both have internal bilinear filtering on, aa 4.0 lvl2, 50% 1080p Scanlines, Reshade smaa, Reshade vibrance 50%, Reshade old Ioxa Gaussian 0.45, and Reshade old Ioxa Boom 0.165):
ScaleFX Retroarch:
https://postimg.org/image/fgcbtulst/
6xbrz Snes9x:
If someone would like to play around with this, i ported a bunch of xBRZ shaders to cg which work in RA. IMHO their quality is between xBR Level2 and xBR Level2 accuracy according to the color metric they use, but hey, i’m not here to decide that. 
They are (as a direct port from cpu version i assume) quite slow, but they are still running full speed on gaming grade HW.
I remember someone giving these to me on the xbrz forums. Was it you? Had a different name though so I don’t think so. But I had told that person that these were a tad off:
Snes9x 6xbrz/RetroArch ScaleFX x9:
Take note on the ridges on the M in Mario Kart that are gone.
Now here are your xbrz shaders:
Look at the M. It has the ridge steps now.
So they are a tad bit off from the Snes9x 6xbrz or the ScaleFX x9 for retroarch (they look the exact same). Those xbrz shaders retain the ridges and steops from the original image, but the ScaleFX and snes9x xbrz totally removes the ridges and makes them a straight line.
Har har, thats funny, i got them some while ago from the same guy, although MAME versions. The difference between the versions is tht mine is in cg and his are glsl, but it doesen’t matter too much. I must confess that i didn’t pay too much attention to xBRZ progress and now i discover that they support blending and higher levels of slopes. Thats competative i must say.
Oh wow! Thanks for porting those to Cg, guest.r! It looks like those have fewer of the tangled, complicated boolean comparisons than the regular xBR shaders, so I might have better luck porting them from Cg to Vulkan.
FAKEDIT: lol, yeah, 6xbr went over with only a handful of very minor changes. Awesome!