Is there any sort of upscaling or whatever for Wii games when played on a Wii U? Most games I don't mind the jaggies, but with games like Xenoblade Chronicles, while the aesthetics are amazing, the graphics are hit pretty hard by the texture resolution and the lack AA.

Most games look better due to the higher resolution the Wii couldn't possibly produce.

It should be noted that Xenoblade uses a pretty primitive engine that doesn't really look great when upscaled. There's just not enough detail in those characters. Environments look fairly pretty but... well, HD environments make it hard to go back to even Xenoblade's.

The Last Story and Pandora's Tower do the upscaling thing much better.

Skylanders: Spyro's Adventure looks really awful and even, at times, pixelated(I think it's trying to tell me something).
Super Mario Galaxy 2 looks just as amazing.
I haven't played any other Wii games on my Wii U.

I'd agree that most of the games i've tried so far do look better, I have a whole load of Wii games still to try out. So far I tried Williams Pinball Classics and Anno, which both look really clear and vibrant. I also re-downloaded some Wiiware demos - And Yet It Moves, Nyx Quest, Hydroventure etc. which mostly looked great.

Wii Sports is the only game i've tried so far which looked worse than on normal Wii, it looked pixelated and all those sharp blocky edges clashing with each other wasn't nice - particulalry on the bowling.

Skyward Sword looks... different. I don't know what's different or why, but it does.

i started skyward sword again the other day looks ALOT worse than i remember to be honest very pixely

I've tried a handful of Wii games on my Wii U, and most have looked more or less the way they did on Wii. The one exception so far has been New Super Mario Bros. Wii which looks worse than I remember it. I was a bit surprised because I am not on an HDTV, so I didn't expect there to be any difference in quality, but maybe I'm just spoiled by NSMBU's sharper visuals.

I tried Epic Mickey 2 on my original Wii,but it had some bad frame-rate problems,popped it into my Wii U and the frame-rate troubles went.