Stands are the physical manifestation of the spiritual and mental strength of someone, therefore, reflects a part of their personalities. Most Stands have special powers that allow their users to have easier lives.
Here are the rules...
1. Stands function in accordance with their users' commands.
2. A Stand can only be attacked by another Stand. However, some Ghosts, Spirits, Engkantos, all Gem weapons, the gods, angels, demons, and Beyonds are exceptions as they are creatures beyond the physical world.
3. When a Stand is hurt, the User is injured by equivalent gravity.
4. When the user dies, the Stand disappears as well and joins the User's spirit.
5. When the Stand is destroyed in the physical realm, the user is killed with it.
6. The maximum and minimum strength, speed, durability, and precision within the given Stats of a Stand are inversely proportional to the distance between the Stand and the user.
7. No Stand is actually weak, as all known Stands can be used for utility and all can be used as weapons. Therefore, there is such a thing as a "smart" or "stupid" way of using your Stand.
8. Standoids, the virus Stands come from, are a genetic disease. Thus, Stand Power is inherited.
9. A Stand-User will only have one Stand unless they are what they call a "Fusion" like Miguel JoJo (Grimm) or Josuke Higashikata (SBR).
10. Depending on the personality and therefore potential of the user, a Stand has the ability to develop.
Note: This is loosely based on the Stand rules Araki wrote in Steel Ball Run Untitled Chapter 3.
They can be in the form of objects, animals, or mostly, humanoids. An example of a Stand is Miguel JoJo's Star Platinum, which is a Stand that continually evolves for an unknown reason. Stands have different Stats altogether...
Only organic organisms are allowed to have spirit guardians called Stands.
Power:
Infinity=Infinity
U=Universal Destruction and Beyond at full power. Users can destroy Universes at full power.
S=Planetary Surface Destruction to Intergalactic Destruction at full power. Users can destroy multiple galaxies at full power.
A=Building Destruction to City Destruction at full power. Users can destroy high-speed-moving meteors.
B=Wall Damage at full power. Users can destroy rocks and bend metal.
C=Average Human-Level Strength. Users can destroy wood at full power.
D=Human Child Level Strength. Users can only damage others if their speed is at B level above.
E=Rat Level Strength. Users can only damage others if their speed is at A level above.
F=Ant Level Strength. Users can only damage others if their speed is at S level above.
Z=Dust Level Strength. Users can only damage others if their speed is at U level above,
0=No Strength at all.
Speed:
Infinity=Infinity
U=Beyond Speed of Light at full speed
S=Speed of Light at full speed
A=Speed of Lightning at full speed
B=Between Speed of Sound and Speed of the Fastest Bullet at full speed
C=Average Speed
D=Slow
E=Very Slow
F=Slower than Clock's Tick
Z=Little to no movement
0=No movement
Range:
Infinity=Infinity
U=Beyond Planetary
S=Maximum of Earth-sized radius
A=Maximum of 1000 meters radius
B=Maximum of 50 meters radius
C=Maximum of 15 meters radius
D=Maximum of 7 meters radius
E=Maximum or 3 meters radius
F=Maximum of 1-meter radius
Z=Stand can barely leave the body.
0=Stand cannot leave the body
Durability (and Stamina):
Infinity=Infinite durability and stamina.
U=Immune to Universal Level Damage and has near-infinite stamina comparable to someone who is a Saiyan, Kryptonian, or Fortisite.
S=Immune to Galactic Level Damage and has stamina comparable to a speedster.
A=Immune to Nuclear Bomb and has stamina comparable to a Hulk.
B=Bulletproof and has stamina comparable to a supersoldier.
C=Average human durability and has the stamina of a regular adult human.
D=Child Level Durability and has the stamina of a child.
E=Insect Level Durability and has the stamina of a sloth.
F=Dust Durability and has the stamina of a baby.
Z=Nigh-Nothing Durability and has the stamina of a Koala.
0=Stand cannot be touched and does not need any stamina to function.
Precision:
Infinity=Infinite Precision and Accuracy. 0% possibility of failure.
U=Nigh-Absolute Precision and Accuracy. 1% possibility of failure.
S=Extremely High Precision and Accuracy. 10% possibility of failure.
A=High Precision and Accuracy. 20 % possibility of failure.
B=Above Average Precision and Accuracy. 30% possibility of failure.
C=Average Precision and Accuracy. 40%-60% possibility of failure.
D=Below Average Precision and Accuracy. 70% possibility of failure.
E=Low Precision and Accuracy. 80% possibility of failure.
F=Extremely Low Precision and Accuracy. 90% possibility of failure.
Z=Nigh-Nothing Precision and Accuracy. 99% possibility of failure.
0=Stand does not need Precision to function and Accuracy.
Potential:
Infinity=Infinity. The Stand can infinitely grow its power and become more powerful. The Stand is at its weakest form.
U=Nigh-Infinite Learning Potential. Nigh-Infinitely a High possibility of growth.
S=Extremely High Learning Potential. Extremely High possibility of growth.
A=High Learning Potential. High possibility of growth.
B=Above Average Learning Potential. Above Average possibility of growth.
C=Average Learning Potential. Average possibility of growth.
D=Below Average Learning Potential. Below average possibility of growth.
E=Low Learning Potential. Low possibility of growth.
F=Extremely Low Learning Potential. Extremely Low possibility of growth.
Z=Nigh-Nothing Learning Potential. Nigh-Infinitely a Low possibility of growth.
0=No Learning Potential. The Stand cannot or can no longer grow its abilities and cannot become more powerful as it is in its most powerful form.