The Primal Bakugan gain a small increase in power and perhaps an ability, but the Primal stage is extremely dangerous. During the Primal stage, a Bakugan, often encouraged by their owner, must suppress their inner darkness. Bakugan who are unable to do so remain as Primal Bakugan forever, as battle-craving weapons ruled by emotion. However, the lucky Bakugan who are able to suppress their emotions evolve a second time, to the X Stage, the best example being RavenoidX.
In the X stage, Bakugan have a rather large increase in power, and will almost certainly gain a new ability. Few Bakugan, however, have the willpower to reach the X stage, and often stay Primal. It is for this reason that Jason is reluctant to use this process.