Sakaki holds dual roles as Viridian City's Gym Leader and head of the criminal organization Team Rocket. He commands Team Rocket operations targeting rare Pokémon theft and advancing his ambitions, including a hostile Silph Co. takeover where he threatens employees for the Master Ball. During this event, he battles and defeats a trainer named Red. His known Pokémon are Rhyhorn, Nidoqueen, and Kangaskhan, with Rhyhorn typically his first choice in Gym battles.

Later, during Red's challenge at Viridian Gym, Sakaki initially uses his standard team but switches to his strongest Pokémon upon recognizing Red's resolve. As the battle intensifies, Sakaki feels unexpected excitement, especially witnessing Red's dynamic bond with Charizard. This rekindles childhood memories of his own passion for battling, contrasting his current view of Pokémon as mere criminal tools. After his defeat, Sakaki offers Red the Earth Badge as Team Rocket's leader, but Red refuses. Sakaki then reoffers it as the legitimate Gym Leader, which Red accepts.

Immediately after the battle, Sakaki announces Team Rocket's dissolution to his subordinates, acknowledging his rediscovered respect for Pokémon beyond their utility in crime. He expresses his intent to abandon his role as a crime boss and pursue a new path. Other media, such as Pokémon Generations, depict Sakaki evading capture following Team Rocket's collapse, highlighting his resilience despite the organization's disbandment.