Oh I have got a really good idea for an intro. This will be for all the sword haters.
Link, Robin, and Marth come out of the woods into a rocky valley. The camera pans around and you see Isaac sitting on a rock. Isaac sees them and vets up into a fighting stance. Robin says, oh he only has a sword *and starts charging Thoron*. Isaac gets his angry face bubble over his head, ththe caption appears "Isaac shakes it up" and when Robin fires Isaac shoots a rock pillar out of the ground. The pillar takes the hit and explodes, dust covers the area. Suddenly vines come up and catch Marth immobilizing him. The ground splits open and Link and Robin get seperated and Robin looks up to see Isaac calling down Ragnarok. Then gameplay ensues.