Stellar Energy Absorption: Inheriting his father’s energy-based powers, Genis-Vell could absorb stellar energy, giving him enhanced strength and durability, flight, and the ability to fire photonic energy blasts. 

When Genis' mental state became unstable, he no longer held himself back in regards to his powers, which increased exponentially, especially when coupled with the Nega-Bands. He began using his powers in ways he hadn't before, such as choosing to project energy blasts through his gun, for visually dramatic purposes, and absorbing multiple forms of energy as well as opening various trans-dimensional shunts that could access various points in space/time and different realities/dimensions. This also appeared to be his level of power after physically being reborn and absorbing the Nega-Bands into his body, which was transformed into pure photonic energy.