He uses this technique several times in Dragon Ball Z: Broly - The Legendary Super Saiyan and Dragon Ball Z: Broly - Second Coming. Aside from it powering him up, it is also implied that it allowed him to break through his father Paragus' control of him via Broly's Ring.
Video Game Appearances
It is first introduced as a Blast 1 in the Budokai Tenkaichi series and a Super Attack in Raging Blast series. When it is used in the Budokai Tenkaichi series, it puts Broly into MAX power mode, and his Attack, Defense and Ki strength go up. When used in the Raging Blast series, he is unable to flinch and his Attack strength goes up.
Broly also uses this technique in Dragon Ball Z: Attack of the Saiyans to raise all of his stats: Attack, Defense, Accuracy, Evade, and Speed.
It is called Defeat Kakarot! in Dragon Ball Z: Supersonic Warriors 2, also used by Majin Vegeta. This ability increases the user's attack power when fighting Goku.
While not an actual attack in Dragon Ball Z: Shin Budokai - Another Road, Future Broly was implied to use this technique in cutscenes to break free of Future Babidi's hold on him, similar to how Majin Vegeta broke Babidi's hold on him.
In Dragon Ball Heroes, using several versions of Broly together can use a combined Kakarot! to raise their powers.
"Broly's Z-Soul. Attacks received do not cause stagger until Health lowers to a certain level."
— Dragon Ball Xenoverse Z-Soul in-game description
In Dragon Ball Xenoverse, it appears as Broly's Z-Soul Kakaroooot!! which can be equipped by the Future Warrior. When the Z-Soul is equipped it increases the users health stat by 2 and Basic ATK stat by 5 though decreases both Strike Supers and Ki Blast Supers by 4. It also prevents the user from staggering when attacked until the wear's Health lowers to a certain level. The Kakaroooot!! Z-Soul can be obtained in Parallel Quest 51: "Heated, Furious, Ultimate Battle".
This technique appears in Dragon Ball Z: Dokkan Battle as Legendary Super Saiyan Broly's Active Skill where in addition to maximizing his Ki, it also massively raises Broly's attack during the same turn the Active Skill is used.