The stage has been changed, with the text now saying punch out, and The floor design having the double gloves instead of the smash insignia, clever Sakurai....
Regarding little mac, He acts VERY quickly out of Dodge, which i hope will become the norm for all smashers this time around, and He appears to have a counter move, a (crappy) uppercut recovery, and Super armor for some of his attacks, as well as an apparent charge meter above his character icon.
edit:
thanks to @
Dravidian
for noticing this
Sakurai: His biggest feature is his Power Meter. When this gets charged up, his standard special move changes! It turns into a one-hit-K.O. uppercut.