My take on the Naruto 'teleportation' jutsus cus they're hard to actually tell apart so I made rules for them.
Kawarimi/replacement
Tag an item with a chakra thread and then swap places with it. Can be done before the battle on items and swapped with when they are out of sight or mid-battle on things you can see.
Walls restrain chakra threads so you can't kawarimi through a wall and people with any kind of sensing capacity might be able to see the strings.
Depending on control, strings can be made thinner or bendier so they can fit under a door gap/be harder to see and shit like that but it requires high chakra control.
Shunshin/body flicker
Kawarimi but with air.
Relies on line of sight and is much harder than kawarimi because you have to tag a pocket of air (aka a shit tonne of air molecules) instead of a single item.
Same downsides of 'people can see ur chakra strings' and 'can't go through walls'.
Hiraishin
Uses a time-space dimension to pull the person to a seal. This is done by attaching a chakra string to a seal and threading the string through a slip dimension.
The person has to constantly maintain the low-chakra required strings which can add up depending on how many you have placed. If the ninja lets go of the strings then they loose that link until they physically go to it and remake the link.
They can be kept up during sleep unlike most jutsu due to the seals making them a passive bodily process similar to chakra keeping the heart beating etc.
In my opinion each string takes about a fifth of a (non-shadow) clone to maintain but the further that string stretches, the more chakra it will take so a seal in another country may take a full clones worth of chakra compared to a seal 100m away only taking a fifteenth of a clone.
To create a hiraishin the nin needs to identify both their personal chakra seal and to find a way to work that into the time-space dimensional key (essentially the interdimensional address of the slip dimension). After that it only requires tagging the seals with chakra which will form a kind of permanent kawarimi link through the time-space slip dimension and activating that seal will yank the user through the slip dimension and spit them out at the other side.
It is essentially the same technique as the other two but, due to the string being stored in the slip dimension, it ignores the other two's downsides.
The user can use chakra to burn a seal onto objects and people if they already know how to do that with seals, otherwise they gotta use pre-made paper seals.
The reason so few ninja can do it even if the process becomes known is because it takes super high-level knowledge of sealing as no one else can make a personal seal so the user has to have a high enough sealing level to identify and map their seal 'fingerprint'.
This seal can actually be used against the user so anyone who makes a personal seal also adds 'noise' to the seal to disguise its exact form. These usually take the shape of seal elements that directly contradict one another and therefore do nothing.
A personal seal can also be used for anything that involves sealing and their chakra so having arm tattoos that act as backpacks are now possible. Huzzah.
Anyway, yea, this is mostly reference for my own headcannoning and fics but feel free to steal it if you want 👍
