It can control trees at will. It will trap people who harm the forest, so they can never leave.
Using its roots as a nervous system, it controls the trees in the forest. It’s kind to the Pokémon that reside in its body.
This Pokémon is said to devour anyone daring to ravage the forest. To the creatures dwelling in the forest, it offers great kindness.
Through its roots, it exerts control over other trees. A deadly curse falls upon anyone cutting down trees in forests where Trevenant dwell.
It’s feared as a ghost of the forest. Lumberjacks bring along Fire types, which Trevenant hates, when they enter the forest.
— Pokédex entries (via PokeAPI)