I made a bunch of silly things (soundtrack, video game, homebrew manuals) leading up to this DBZ manual. Below are links and short summaries of how the powers work. I didn't really change a lot from canon DBZ, I just explained things and made the DBZ world more logically and numerically consistent.
Concepts of Dragon Ball Z for gameplay
by George Young
This page summarizes some of the content from my original GURPS manual and from my unofficial 5e Dragon Ball manual. The original manual was almost 300 pages due to way too much detail, while the new and improved one using 5e D&D is only 69 pages.
- Super qi is used for super powers. It is separate from regular qi or subtle energy. It has its own associated energetic anatomy where it is stored and this is separate from the regular subtle body, though they are connected. The ability to use super qi is something you are born with through a divine or alien ancestry. Super qi can be absorbed from the environment such as from the sun and the earth as it is a form of subtle energy.
- Powers include:
- Dense Body: Dense body is a form of super strength that increases the energy from strikes, increases physical durability, and increases muscular strength. Super qi is used to generate "internal force" that makes the flesh unyielding and stronger. This affects muscles and tendons to increase muscle contraction ability; it makes limbs able to strike with much more force; and it can be used to absorb damage from attacks. It is a form of semi-unconscious internal energy manipulation based on the complicated and interconnected anatomy of the physical and subtle bodies.
As power level increases, the amount of energy that can be stored for this ability increases. When supers "power up", they are mainly pulling in energy for dense body (increases strength and hit points in the game) as well as energy for their "super qi points" that are used for a variety of powers. Your energy body chakras continuously pull in energy to maintain the dense body effect during combat, so super qi points are not needed for this power. Super qi points may be stored in another "layer" than the energy used for dense body.
Dense body is a complex power possible because those able to use super qi have a different physical and energetic anatomy. Regular mortals can train for decades to achieve a weak version of this power, but supers can learn it much more easily or even without training and they have a much higher power ceiling for this and the other powers listed here.
- Altered Time Rate: Super qi is used to increase the rate of flow of life force qi and to thereby increase the time rate of the individual. For supers, this does not actually create an "altered time rate field" (though it is possible to do that with magic or super science, and this is used for stasis during space travel). It speeds up their movement, thinking, and rate at which they pull in energy, but still requires psychic perception and a superhuman physiology to function at high speeds.
- Flight, gravity control, and high jumps: Can jump really high, reduce or turn off gravity completely, and use a form of super qi manipulation to fly. Flight speed mainly increases with power level and a higher time rate. As power level increases, supers rely on flight more and do much of their fighting in the air. If they are on the ground, they may still rely on a form of flight or gravity control to increase agility. Also, supers can use extra super qi in order to gain a boost to flight acceleration. Supers would typically use the step power rather than accelerate too quickly.
- Telekinesis: The main thing to know is that the farther away the object is, the harder it is to use TK on it. People, other living things, and some artificial beings have spirit bodies or energy fields that protect them from telekinesis being used inside their bodies. TK is much weaker and shorter range than the few times it is used in canon DBZ, the exception being magic users who are slightly better at it.
- Ki blasts/ waves: Ki *wave* is where you project your super qi as a destructive pressure wave. This can be used an attack by itself or combined with an unarmed strike. Ki *blasts* are formed from super qi that is manifested as "burning qi" particles and then fused together into different shapes. Burning qi has mass but doesn't interact with gravity (or else the ki blast user's concentration negates the gravity), and releases stored energy as heat at the surface of the blast while also leaking some as EM radiation (i.e. light). Spheres, rays, kamehameha like beam attacks, and discs are all possibilities and are easier to form than more complex shapes. Ki blasts can be detonated, which releases all the energy inside as heat and an explosive pressure wave.
- Healing: Healing with super qi is possible but not everyone would know how to do it, or even be able. Sages like Kami and those with a divine or angelic ancestry might be able to heal, but most Z Fighters do not have this power. The Sage is a super qi user class that focuses on energy purification, elemental magic, and healing at the expense of not being as good at destruction and fighting.
- Force field: Some users of super qi can manifest a skin-tight force field to provide protection against ki blasts or mortal weapons. Force bubbles that primarily protect against energy attacks are also possible, but otherwise the force field becomes exponentially weaker the farther away you project it from your body.
- Super qi as armor: Super qi can be used to reinforce the body to protect against and diffuse the energy from attacks.
- Step and Teleport: Generally these abilities are very short range and each use costs a significant amount of super qi. Step involves briefly phasing into the hyperspace dimension (explained in the manual), while teleportation occurs at the speed of light and involves dematerializing and rematerializing.
- Psychic Perception: The ability to feel energy can be very useful providing a kind of sixth sense. Psychic perception may include some form of telepathy or a non-linear time sense.
- Power Level: Determines the amount of super qi your energy bodies can store and process. Increases dense body multiplier capable of and the magnitudes of other listed abilities, including the amount of super qi available for powers. Can increase to a point with training. After that point, requires mortal energy from fallen foes or gravity training to increase. Mortals have a limit past which they must use transformations to be able to compete with artificial supers or angels, demons, and other divine beings. Also, unlike in canon DBZ, supers don't go around everywhere powered up. In their base forms they have psychic abilities, wis to ac, and uncanny dodge. Powers such as flight or altered time rate can be used quickly (as a reaction), but pulling in energy for dense body and ki blasts takes time.
- Lifespan: Users of super qi can live much longer than regular mortals. Absorbing Mortal Energy may enable a super to live longer, but using combat transformations frequently drains this life force qi.
- Artificial supers: Includes androids and mortals who have implants that enable them to attain something similar to having a bloodline that grants super qi. Is not good, crystal based implants can make a user more powerful than a natural super but may lead over time to insanity and wickedness. Artificial supers cannot use transformations but are are likely to have a higher natural power level.
- Magic: Some super qi lineages grant the ability to learn various forms of reality warping, which can be fueled by super qi. The most commonly used and simplest form of magic to learn is elemental magic.
- Super Science: This is high technology combined with magic crystals and other exotic and otherworldly materials that exist on this magical version of Earth. The combination of magic and technology is what enables space travel, energy weapons, powered armor and robots, and other cool things in the DBZ universe.
- Transformations: In general, the stronger they are the more life force qi they burn through to stay active and the higher the power level is required to be able to use the transformation.
- Berserk: Anger induced and unstable but increases power level. Hard to maintain for very long. Saiyans are better at it. Dark green color aura.
- Kaioken: Similar in power to berserk but more controlled. Downside is it stresses your body and can cause injuries. Red colored aura.
- Magic Kaioken: Much stronger than kaioken and focuses on spiritual strength rather than just physical. It greatly boosts energy efficiency and amplifies speed and psychic abilities but doesn't direclty boost power level as much as Super Saiyan. Requires many years of mystical training to achieve. Can be a very stable transformation. Considered an "angelic tier" transformation. Color depends on individual (blue is common).
- Super Saiyan: Caused by anger or strong emotions rather than mystical perfection attained through many years of practice. Another angelic tier transformation similar in power to magic kaioken but with some differences. It boosts power level and moderately amplifies psychic ability. Those without Saiyan blood usually cannot use this transformation. Has a lot of sparks and stuff when transforming. Golden aura.
- Divine Transformation: Like Magic Kaioken but on a much higher level. Eats through a ton of life force qi. Are different alignment based versions of it. The good version may provide some healing abilities for instance, and is otherwise like Ultra Instinct. Aura depends on alignment.
- Super Saiyan God: Once again induced by strong, profound emotions and requires a very high power level. Requires a special bloodline typically (i.e. Saiyan). Comparable to divine transformation power-wise but more unstable with sparks and stuff. Greatly boosts power level and psychic potency. Silver aura.
Lots of other powers may exist in your game world and where super qi exists there might also be magic of various forms. What I included is just some of the main interesting parts.
My unofficial Dragon Ball manual based on 5e D&D goes into way more detail about all this, 69 pages of detail!