You probably knew all of this already, but...Here goes nothing.
-Link is the Hero of Time and also the Failure of Speech Classes.
-Although Marth is actually a Middle-Weight, he acts like a Light-Weight.
-The end of Sheik's whip thing is electrified.
-It's easy to dodge Kirby's Final Smash with Zelda/Sheik. Just time your transforming well.
-If you suck in another Kirby as Kirby, nothing happens when you swallow.
-Only one character can grab a ledge at a time.
-Toon Link is faster and lighter than Link, but weaker.
-Link's shield can stop a enemy's projectile in its tracks. Just stand still.
-Using Olimar's down-special not only calls back all Pikmin, but also rearranges the order that they're lined up in.
...That's it. Well, I hope you learned something today. ^.^