The ability to transform into a state beyond Super Form where one's powers and potential are strengthened to a higher degree.
The user can transform into a state beyond Super Form that greatly increases the user's power, giving them an increase in strength, speed, and skills, gain new abilities and have the previous ones strengthened to a higher echelon of power.
The Heisei era Kamen Riders (Kamen Rider Series); via power up items
The Super Ranger forms (Super Sentai); via upgrades, usually reserved for Red Rangers but some can be used by the full team.
Heisei era Ultramen (Ultraman series); via fusing with one or multiple Ultramen or gaining extra power from another source.
Honey Kisaragi's Hyper Honey form (Cutie Honey Flash); via her late sister Misty Honey's Airborne Element Condenser combining its power with hers.
R1 Max and Fire-1 X (Tomica Hero Series); activated via the Max Commander and the X-Basher devices
Superman (DC Comics); via sun-dipping
By using his Alter power at it's maximum, Kazuma (s-CRY-ed) becomes harmonized with his Shell Bullet and is able to access his strongest form, Proud Fist.
Much like Kazuma, Ryūhō (s-CRY-ed) can use his Alter power at it's maximum, becoming harmonzied with his Zetsuei, allowing him to access his Zetsuei Touryudan form.
Hyper Sonic (Sonic the Hedgehog series) is a transformation that Sonic can achieve when he collects all seven Super Emeralds.
Mirajane struass (Fairy Tail) in her strongest form of satan soul.
Gohan (Dragon Ball series) was the first to achieve the Super Saiyan 2 transformation. In this form, Saiyans surpass the power of an Ascended Super Saiyan and an Ultra Super Saiyan, allowing them to increase their strength while maintaining their speed.
Goku (Dragon Ball series) was the first to achieve the Super Saiyan 3 transformation. In this form, Saiyans surpass the power of a Super Saiyan 2, using power extracted from every drop of their blood.
Goku and Vegeta (Dragon Ball GT) are the only known Saiyans to have achieved the Super Saiyan 4 transformation. In this form, Saiyans are at their strongest, with all of their power drawn out to its utmost limits.
In his rage at Goku Black for his actions, Future Trunks (Dragon Ball Super) took on a new, immensely powerful Super Saiyan Rage form.
Type Tridoron is Kamen Rider Drive's ultimate form. It is a fusion of Shinnousuke, the Drive Driver, and all 26 Shift Cars with his car Tridoron acting as the armor.
By "sundipping," Superman (DC Comics) immerses himself in the sun and absorbs massive amounts of solar energy, greatly powering him up.