In Dragon Ball canon, Vegeta is always trying to get stronger, but for some reason, he decided to skip the Super Saiyan 3 form altogether. Why?
Vegeta completely skipped the Super Saiyan 3 transformation in the Dragon Ball franchise. Vegeta has gone Super Saiyan 3 in the video games and the Dragon Ball Heroes web series, but not once has he ever made use of this form in canon.
Easily recognized by the user’s lack of eyebrows and incredibly long hair, the Super Saiyan 3 transformation made its anime debut in Dragon Ball Z’s Buu Saga, when Goku used it to fight Majin Buu. Apparently his intense training on Otherworld gave him the power he needed to go beyond Super Saiyan 2. Goku intentionally didn’t use it when he fought Vegeta, who was jealous of Goku’s newfound power when he heard about it. Goku later taught the ability to Goten and Trunks, who were able to use it after fusing it into Gotenks. At this point, Goku and Gotenks are the only characters who have entered this form, but Universe 6’s Caulifla is hoping to achieve it as well.
Vegeta is certainly strong enough to pull off the transformation, so it’s worth wondering why he never tried it. First of all, it should be noted that Vegeta couldn’t go Super Saiyan 3 in Dragon Ball Z. He simply didn’t have the physical capabilities at the time, as Super Saiyan 2 was the extent of his power. However, Vegeta was powerful enough to use it through the entirety of Dragon Ball Super. In fact, Super Saiyan 2 Vegeta handled himself better against Beerus than Goku did while in his Super Saiyan 3 form. Therefore Vegeta must have made a conscious decision to avoid it.
Super Saiyan 3 has flaws that Vegeta surely knew about, either from observing Goku or by trying it out for himself offscreen. It’s a physically taxing ability that drains the Saiyan of his energy. Vegeta had similar concerns about the Ultra Super Saiyan form, which he has expressed to Future Trunks. Vegeta could easily have shared the same opinion about Goku’s Super Saiyan 3 form and simply decided that it wasn’t for him. When it comes to combat, he’s more tactical than Goku and could have concluded that a better strategy is to stay with Super Saiyan 2.
For this reason, it makes sense that before the Golden Frieza Saga, Vegeta believed that he was better off using Super Saiyan 2 as his primary form. That way, he could fight for extended periods of time. After all, it is an efficient transformation that has served Goku and Vegeta well in both Dragon Ball Z and Dragon Ball Super. Even Goku uses Super Saiyan 2 more than he does Super Saiyan 3. Goku has admittedly dialed back on Super Saiyan 3 in Dragon Ball Super but does return to it when the situation calls for it.
A third factor that may have motivated Vegeta into not using Super Saiyan 3 was his rivalry with Goku. The previous two forms were first achieved by Goku and Gohan respectively before Vegeta was able to get the same results. When considering Vegeta’s pride, it’s understandable that he would have found continuously copying Goku distasteful. Wanting his path to diverge from Goku’s was his reason for foregoing Ultra Instinct and inventing Super Saiyan Blue Evolved.