From Bulbapedia, the community-driven Pokémon encyclopedia.
Pledge Grove (Japanese: 誓いの林 Oath Woods) is a small forest-like location in southwest Unova. It is connected to Floccesy Town to the south. The path here is located directly to the right of Alder's house. The player's mom claims that the marks on the rock were made by Pokémon.
The main feature of the Pledge Grove is a rock with three cuts across it. If the player examines the rock with an Ordinary Form Keldeo in their party, Keldeo will want to come out of its Poké Ball. If the player lets it out, it will excitedly examine the rock, and then is reminded of Secret Sword by the determination of Cobalion, Virizion, and Terrakion that has been carved into the rock. If the player allows it to learn the move, the spirits of Cobalion, Virizion, and Terrakion appear, then zoom away; Keldeo resolves to battle, and is transformed into its Resolute Form.
In other languages