That is not always so. Especially with the auto-sweetspotting system in Brawl. Some characters are at a ridiculous disadvantage when certain characters ledgecamp against them. It's simply how the game works. Go take agressive action against a Planking MK as Falco. You'll find that you have very little options if the MK player is competent.
I'm assuming MK is using shuttleloop to autosweetspot the ledge?
First of all, I would never use falco against MK, but let's assume for some reason I'm forced to use a character I don't use against some pro's MK, shall we?
I'm standing a little bit inwards from the stage, so I avoid getting hit by MK's shuttle loop (scary little booger). He shuttleloops over and over again...SUDDENLY, nothing happens. I continue to watch MK repeatively SL'ing. SUDDENLY, I speedhug the ledge and MK dies. simple enough?
If he isn't use SL and just dropping down and jumping back up:
I can run of the edge and bair, which should stage spike him.
I can just regular spike him
I can footstool him (always an embarrassment)
OR I can walk over to the other side of the stage, set my controller down, and Laugh at him.
The olimar video was to prove a point...