I'm not sure if this has been touched apon this yet but it's something I discovered at the Falling Cliffs arena while playing Arcade mode last night.
I was Hotaru fighting Ermac and he knocked me into the pit. To my surprise just as he did the edge of the cliff he was standing on broke away and he came toppling over the side with me. It showed us both falling together and we both were impaled on the rocks right next to each other.
It gave Ermac the victory assuming since he knocked me in the pit first.
I thought it was a nice surprise. Definitely not an SU but a nice surprise none the less!