Emulation is not allowed. That's just about it, really.
GCN emulation is allowed for Enter the Dragonfly due to it being accurate enough, so that could possibly be allowed at some point. It could be pretty good, considering how GCN is the optimal version along with Xbox if you don't account for loads. Removing loading times could also be looked into at some point, but whatever. We'll see.
Of course I did, that's why I asked in the first place.
From what Dustiel said, GCN emulation could be allowed "at some point" and well, that post is 2 years old so I'm bringing it back up to see if things changed since then.
Dolphin has been getting pretty accurate lately, so I wouldn't be surprised if it became allowed at some point in the future.
PS2/XBox emulation is still quite far off, but GC is "close".
