I'll be updating the list in a minute, I found a few more things and left out a game that I tested originally.
Also, yes, Pikachu's voice is mutilated, and all I can think of is that PCM sound isn't emulated properly (if that's what the format is, I just know that 'voices' in Sega games are called PCM format).
EDIT: This may also just be me, but give Kirby's Dream Land a test and see if you spot the graphics chugging but staying at 60FPS. It seems to me that some games including that are being forced through a possible throttle to stay at 60FPS, resulting in what appears to be a skipped frame or general non-smoothness. It's very hard to spot, but I notice it.