"Beerus: Goku's using his brain for a change!
The Super Saiyan God-to-Blue switching technique is an energy conservation tactic invented by Vegeta in the manga and Goku in the anime, in which they rapidly switch between the Super Saiyan God and Super Saiyan Blue forms in order to utilize Super Saiyan Blue's power to its full potential.
Super Saiyan Blue's vast strength comes at the cost of rapid energy consumption, meaning that the user cannot maintain the form for long. To overcome this weakness, the user remains primarily in Super Saiyan God form, maintaining a speed advantage, and only transforms into Super Saiyan Blue in the very instant that they attack or defend, at a speed that can make it seem like the transformation switch hadn't even happened. This allows the user to conserve Super Saiyan Blue's power along with their own stamina and then let it explode when necessary.
While the technique originated in the manga with Goku during his fight against Hit in the Tournament of Destroyers, he was only able to perform the switch a single time. Vegeta later trained extensively to complete the technique, using it repeatedly to overwhelm Goku Black despite the latter seemingly having the advantage in Super Saiyan Rosé form. Much later during the battle against Moro on Namek, Vegeta transitions in a similar but a bit slower manner to Blue form from Super Saiyan God in order to repel away Moro's energy manipulation attack.
In the anime, during the Tournament of Power, it was Goku who finalized the strategy instead of Vegeta, and used the technique during his impromptu tag-team with Hit against Dyspo and K'nsi. With the rapid switches, Goku was able to force Dyspo on the defensive, able to read and counter Dyspo's linear and predictable movements. This display leaves Beerus and Whis highly impressed, the former exclaiming "That's our Goku" while the latter explaining how the momentary changes from God to Blue allow him to maximize his speed and power without draining his energy.
- This technique is very similar in usage to Goku's early use of the Kaio-ken, activating a state of much higher power for a fraction of a second to overwhelm an opponent or increase speed.