Super Saiyan Spark

Super Saiyan Spark (also known as SSS or Triple S) is a unique and exclusive transformation both Goku and Vegeta obtain during their battle with Broly in Dragon Ball Super: Broly. Goku and Vegeta gain the 'spark' add on to their Super Saiyan forms through the Paragus' Gauntlet, the same gauntlet that's aiding Broly, generating and controlling his limitless energy.

The Saiyan pairing fire a joint Kamehameha-Big Bang Attack at Broly. However, Broly deflects this attack at Paragus, disintegrating him, also destroying the gauntlet. The gauntlet explodes with immense energy, catching Goku and Vegeta in the shock-wave. According to Piccolo, the Legendary Super Saiyan's DNA is fused within the gauntlet, allowing Paragus to control Broly. In addition, the gauntlet has been granted some of Broly's unlimited power, allowing Paragus to take command and defend himself against Broly if required.

Super Saiyan Spark Goku and Vegeta are slightly weaker than Broly at full strength, but are more capable than their previous forms. Super Saiyan Spark utilizes the user's full potential and hidden strengths, much like Legendary Super Saiyan. It provides a major ki efficiency and regeneration boost. It has about the same, if not more strength than Super Saiyan Blue, but possesses key abilities which eventually led the downfall of Broly.

Toriyama states that Super Saiyan Spark may appear again in later installments.

Appearance
Super Saiyan Spark is similar in appearance to regular Super Saiyan. However, sparks or lightning and a lighter aura can be seen radiating from the Saiyan. Goku and Vegeta also appeared to have more muscle mass, similar to Super Saiyan Grade 2. Whilst activating ki-based attacks, Goku and Vegeta's appearance swayed more towards Super Saiyan Blue, displaying the form's contribution to Super Saiyan Spark's power.

Goku and Vegeta vs. Broly
Eradicating the area, Paragus' Gauntlet seizes and Goku and Vegeta are caught in a devastating shock-wave. Broly's power continues to increase and it's just a matter of time before his energy destroys the planet. Rising up, Goku and Vegeta appeared to be damaged by the martyr. They try powering up and suddenly, a spark activates within their Super Saiyan Blue forms, reverting back to their golden hair forms and transforming finally into a Super Saiyan Spark.

Broly rampages towards them, ki destroying all atmosphere around him. Goku unleashes a hidden ability, voiding Broly into the other-side of the planet using Instant Transmission. Goku and Vegeta discuss a plan of action, but notice Broly rummaging through the planet. Goku and Vegeta fight Broly, with Broly having the upper-hand. Goku tries a Kamehameha again, but this time, it increases in power and startles Broly, leaving him open for Vegeta's uppercut.

Meanwhile, Gohan, Piccolo, Krillin and Bulma work together to create a device that can place Broly under control.

Broly launches a wave of enraged energy, taking both Goku and Vegeta out completely. Gohan fires an unleashed Kamehameha at Broly from the fortress window, attracting Broly's attention. Goku notices Broly's ascendance towards the fortress and stops him using Instant Transmission. Broly strikes Goku down.

Vegeta crawls his way to Broly and kicks him off of Goku. As a final hope, Goku activates Solar Transmission and teleports Broly into the vacuum of space. However, this leaves Goku completely depleted.

Bulma finally pieces together a device similar to Paragus' and hands it to Piccolo, which Piccolo gives to Vegeta. Broly powers up a meteorite-sized energy sphere and launches it at the planet. Vegeta presses the button, disabling Broly but leaving the sphere plummeting to the surface. Vegeta, Gohan, Piccolo and Krillin use their energy to try and push it away. Suddenly, Super Saiyan Spark reactivates and Goku and Vegeta regenerate their energy. Now at close-to-full strength, they use all of their power to throw the sphere into Broly himself. Neutralizing him.