Dragon Ball: The Mysterious Teacher

Bo Te transmigrated into a Saiyan and unlocked the “Teacher” System.

As long as he taught a student, he would gain fifty times that student's base battle power.

From the start, he successfully guided five-year-old Vegeta into transforming into a Super Saiyan.

From then on, Bo Te set out to lie flat.

As Vegeta grew stronger, Bo Te's base battle power increased fiftyfold on its own, and transforming into a Super Saiyan could boost it another fiftyfold.

…

Several years later.

Bo Te: “Vados, become my student!”