I’ve been playing around with the Dolphin core recently and I found out something strange. I have a 2560*1440 monitor on my PC, I always have Integer scale = ON in Retroarch.
In the Dolphin core, I can set the internal resolution to the maximum (x6) on 16/9 games like Soul Calibur 2, it looks amazing. But if I switch to a 4/3 game (like Luigi’s Mansion for instance), it gets stretched in every internal resolution that exceeds my monitor resolution. Which means that the game displays correctly in 4/3 with internal resolution set to x1 or x2, but from x3 to x6 it gets stretched to 16/9 and looks terrible.
Edit : setting Wide-screen to OFF in the core options does not help.