And that speed is:
Distance/0 seconds..? It's impossible to divide by 0.
Teleportation is the transfer of matter from one point to another without traversing the physical space between them. So there is no distance traveled either. It's simply disappearing and reappearing somewhere else. You aren't traveling any distance.
it is not impossible. It is undefined.
0 is a placeholder basically. Our understanding of science hasn't caught up yet to understand this.
If you think we've already explained everything and we understand all... well I need not respond more.
You still have a displacement. Displacement is your relative change in position. v = d/t
Since You are no longer at your starting position and your displacement isn't 0, then you have moved. Displacement is variable and you can take that into account. The fact that the person cheats time by warping through another dimension and back changes nothing.
If you stand in the same spot for 5 minutes, your speed is 0. If you move from kyoto to new york in 0s your speed is just too great to currently comprehend.