A short basic CLSN tutorial for all characters by K.O.D
CLSN2 : Collision box (Blue)
CLSN1 : Hit box (Red)
KoF : King of Fighters.
Keep in mind all these :
1.If the character is a KoF character, take the CLSN data directly from
KoF which is much simpler than explanation.
2.2 CLSN2 boxes on each animation (maximum 4 boxes)
3.1 CLSN1 box on each animation (maximum 2 boxes, but it can be
increased to 4 if the animation is of a slanted projectile,etc.)
4.Position your boxes a bit out of torso range but within the arm's
range.
5.Always use the same CLSN boxes in the standing animation, do not
change the clsn boxes in any frame of the standing animation.
6.Use CLSN Default for a CLSN1/CLSN2 box which is the same in all
frames.
7.Do not make the CLSN boxes move unnecessarily in the animation just
for a single limb or head movement,etc.
Note : Even though the character I'm using as an example for this
tutorial is a KoF character, I will change his CLSN boxes just for the
sake of demonstration.
An example of good standing CLSN2 boxes (clean and practical)

An example of bad standing CLSN2 boxes (too many and causes lag)

Another example of bad standing CLSN2 boxes which are caused by
spriteswapping (completely out of place)

Now moving onto CLSN1 boxes, there is a thing known as "infinite
priority" which is caused by not overlapping a CLSN1
box with a CLSN2 box which in turn makes the attacker "cheap" by
allowing him to attack without getting hit back.
Also, swords or any other weapons do not need to have a CLSN2
overlapping the CLSN1 boxes on them.
There's also another issue with KoF characters which have a different
CLSN system in which the CLSN2 boxes have only a
a small portion of the area covered while the rest is not covered, its
recommended to follow KoF CLSN boxes just for the
sake of accuracy.
CLSN1 boxes must be within in the range of the hand/sword/etc. and not
covering much more (however, sword "slashes"
can have a wider CLSN1 box to give accuracy to the slash)
I will give the examples based on non-KoF clsn boxes.
An example of good attack CLSN1 boxes (within range and practical)

An example of good jumping attack CLSN1 boxes (within range,practical
and does not need multiple boxes)

An example of bad attack CLSN1 boxes (huge,has infinite priority and is
unrealistic)

An example of bad jumping attack CLSN1 boxes (too many boxes,has
infinite priority and is unrealistic)

Same rules apply for projectiles, keep them within range and keep them
clean.
Projectiles need to have a CLSN2 box covering the CLSN1 box (even in
KoF characters) for getting hit by other projectiles/blocking other
projectiles depending on what type of projectile you are coding.