It's not something worth doing unless the opponent is really far away, and it's mostly to create a false sense of opportunity or to sorta mix up your teleports. It's not really viable as any kind of movement because of the lag.
It's not instant KO, but it can gib people who panic on stages with ledges like battlefield. Basically you can do it two ways, I prefer to just press back, then when I've let go of the ledge I press forward and B while they're still in range. Some people tend to ledge hop, meaning you drop off of the ledge by pressing back or down then double jumping to rise high enough to hit with confusion.
Either way works, but I prefer to keep my double jump with my method just in case I play some tricky people, but the other way usually puts you in a position to just sweetspot the ledge with teleport, so assuming everything goes to plan, you'll get their first.
It's not instant KO, but it can gib people who panic on stages with ledges like battlefield. Basically you can do it two ways, I prefer to just press back, then when I've let go of the ledge I press forward and B while they're still in range. Some people tend to ledge hop, meaning you drop off of the ledge by pressing back or down then double jumping to rise high enough to hit with confusion.
Either way works, but I prefer to keep my double jump with my method just in case I play some tricky people, but the other way usually puts you in a position to just sweetspot the ledge with teleport, so assuming everything goes to plan, you'll get their first.
But I had this dope down air chain going on this Sheik. 
But you're right usually if they're kinda timid you can float a little bit over him and then DJC forward or backards into the down air. Not spammable, but still good every once in a while.
