Pokémon - Rest in f------ pieces

That's how it reproduces.

"Sunabaa is a grudge that dwells inside a pile of sand turns into a Pokemon. Truly a terrifying creature
Shirodesuna steals the life force from other Pokemon. Those Pokemon's grudges turn into a new Sunaba."

It kills other Pokemon by draining their life force, and the dead Pokemon becomes its pre-evolution.

well, since you asked