The WKC an be performed 2 different ways. The easiest way is to roll TO THE VERY EDGE of the stage and perform a Wizard's Foot(Ganon's Down B) towards the stage. At the end of the move Ganon will roll in the air instead of the move just ending.
The second way is more difficult, as you have to know how far the move actually travels. Firstly you have to face the edge of the stage at exactly the right distance which is as far as the Wiz Kick goes. Then you perform the Wizard's Foot towards the edge. If performed at the correct distance Ganon will simply fall off the edge. If done incorrectly, you will either not make it to the edge, or will go too far and Ganon will do the roll animation.
So why is this useful?? The rolling animation dosn't do anything!
Well, During the rolling animation, you can use an aerial move, a side B (Flame Choke), another Wiz Kick, which will create the "Quake Stomp", an Up B, or a Flight of Ganon (FoG).
FoG guide can be found here: https://eptcnextgen.forumotion.com/t455-flight-of-ganon-fog#11581
The WKC is also useful, as at the end of a normal Wiz Kick, there is quite alot of ending lag. With the WKC, the ending lag is canceled with whatever move you imput during the roll animation, so it is a very good technique for aproaching.
Thats about all I can be bothered to type at the moment, but I will finish this guide sometime over the weekend.
As always if you wat me to show you this technique then dont be afraid to post here or send me a pm =D
I'll also do a seperate guide for Captain Falcons cancel