Contrary to what their names suggest, the Super Saiyan 2 form is actually superior to the Super Saiyan 3 transformation in the Dragon Ball franchise.
Contrary to what their names suggest, Super Saiyan 2 is actually a better transformation than Super Saiyan 3 in the Dragon Ball franchise. When it was first introduced in the Buu Saga, the Super Saiyan 3 form was seen as a step-up from the previous power level and the most powerful variation of the Super Saiyan transformation. However, much has changed since Goku battled Majin Buu and taught the technique to Goten and Trunks in Dragon Ball Z.
In Dragon Ball Super, Goku moved beyond Super Saiyan 3 when he unlocked the Super Saiyan God and Super Saiyan Blue forms. Toward the end of the anime, he grew even stronger when he discovered Ultra Instinct, a transformation that isn’t connected to his Saiyan heritage. Since Goku and Vegeta now have access to varying levels of power, they don’t always stick with Super Saiyan Blue, as sometimes it’s necessary to conserve their strength for more difficult fights. When that happens, the two rely on weaker forms like Super Saiyan 2, an ability that was first used by Gohan all the way back in the Cell Saga. It looks visually similar to the standard Super Saiyan form but can be recognized by the sparks of blue lightning around the user’s body and the slight difference in the hair.
Even though Super Saiyan 3 was supposed to be the next level above it, the Super Saiyan 2 form is favored by both Goku and Vegeta. It’s a better transformation because the Super Saiyan 3 state drains too much energy too fast. That was one of the biggest problems that Goku had with it when he was fighting Kid Buu. When he used it as a demonstration in his fight against Caulifa and Kale in the Tournament of Power, he only stayed in it for a brief period before going back to Super Saiyan 2. That was because Goku was tired at the time, and he knew that Super Saiyan 3 would exhaust him considerably.
Super Saiyan 3 is indeed more powerful than Super Saiyan 2, but the rate at which it consumes the Saiyan’s energy takes away from its effectiveness in combat and the length of time in which it can be utilized. That’s why Goku thought he could do better against Caulifla and Kale if he used Super Saiyan 2. It also makes sense of why Vegeta never went Super Saiyan 3 (despite having the power to pull it off throughout Dragon Ball Super). Vegeta likely understood from observing Goku that it was a heavily flawed form and that the level preceding it was more efficient. It’s also worth noting that at the beginning of Dragon Ball Super, Super Saiyan 2 Vegeta was able to put up a much better fight against Beerus than Super Saiyan 3 Goku.
This helps explain why Super Saiyan 3 has lost its relevance to Dragon Ball, and why Super Saiyan 2 hasn’t. When Goku was trying to save his best for fighters like Jiren and Top, he often fell back on the Super Saiyan and Super Saiyan 2 forms, which helped him get through several challenging fights with Kale, Caulifla, and more.