Citrus clip is a method of Teleporting that works with ◣ slopes. It can be done in the underworld and overworld, and it can be done without Boots. For more info see: Citrus clip
Dash Buffer Clipping
Using Dash Buffer Clipping techniques, you can activate teleports on ◣ and ◢ slopes on the overworld. This method will NOT work in the underworld.
Every teleport has at least two consecutive working y-coordinates to begin the clip at: coords ending in
xxC-xxD. Certain teleports will have more working positions and occasionally a teleport will have a specific enough goal that only one position works, but this is a good place to start from.
From a beginning y-coordinate position, Dash Buffer Clip into the slope either 8 pixels (for an upwards teleport) or 9 pixels (for a downwards teleport). When you get to the position you want, buffer diagonal towards the slope (ie.for ◣ slopes) to Teleport. Because Dash Buffer Clipping will typically involve charging a spin attack, the spin animation is a useful buffer for the diagonal to trigger the Teleport.
It is important to be familiar with Link's Movement mechanics while Dash Buffer Clipping for Teleports. When you're clipping to Link's right, he will move 1px each time you dash buffer into the slope. This can make ◢ slopes hard to clip fast and consistently since you'll need more successful buffers to reach the correct position. If you're clipping to his left, he will move 2px each time you dash buffer into the slope. This often means that if you're trying for a downwards teleport on a ◣ slope, you'll have to clip 10px in and 1px back out away from the slope to get in the correct spot.
For more specific information on various Teleports useful for Speedrunning, check Clips.