From what I've tried on my n3DS:
Mega Man 8: 60 fps (50 on FMV), no slowdown in gameplay with frameskip = 1, scratchy sound, sped-up voice clips, a couple missing graphical effects I think
X4: 40-45 fps, has visual glitches, scratchy sound
Legends 2: 40-45 fps, scratchy sound
Sadly, 8 is one of...