Teleports in Mario 64 are well, teleports.
There are two types of teleports.
Warp Teleport: A teleport to another course. Can take a place of an painting, a spot in 3D space, or a death warp - warp to another stage when you fall into an bottomless pit.
The more important teleport, of course, is the Standing Teleport. The Standing Teleport teleports Mario to another location in or outside the course but only if he takes a moment to stand in the location of the Standing Teleport.
In Super Mario 64, Warp teleports are only used for secret stages or little details, while Standing Teleports are used only for secret shortcuts.In rom hacks, Warp teleports are normally used just like in Super Mario 64, but Standing Teleports are hidden almost everywhere. Standing Teleports will probably have destinations of quicksand in these romhacks, or they might be the only way to get to a certain star in the romhack. They are a timewasting terror to Simpleflips and Mario everywhere, as it is completely impossible to even see teleports at all, as they are completely hidden from the naked eye unless one uses a level editor to see the teleports.