Just fixed it! Do you guys have any knowledge on how to stop the flickering effect?
If you're constantly redrawing a sprite, it might flicker depending on how much code you have between sprite draw commands. You might be able to hide it by increasing the emulation speed to 200 or 500 cycles per second. Of course, this will also increase the speed at which your game runs, so unless you have a delay function in your code, be careful!
There's a section in the FAQ which goes into detail on this topic: How do I keep my program from flickering?