I don’t have an OLED, but I have been running through Wind Waker HD on my Deck. Takes a minute to get used to switching the screen with the button on the back, but they run great.

Every Wii & WiiU game I’ve tried has run smooth except for Breath of the Wild. I just stick with my Switch for that one. Also DS/3DS games I play on my 3DS to keep the touch screen functionality since many games use that for controls. I haven’t tried DS/3DS on the Deck yet. Having far too much fun playing Gamecube/Wii/WiiU games I missed out on over the years.

Switch games in general run really well too now with 3.5. Before that they had bad framerate dips.

I’ve had good luck with every console up to Xbox360 and PS3. 360 & PS3 are very sluggish.