Grotto Spawner
From Pixelmon Wiki
A grotto spawner is an item that can be only obtained by spawning it in. It can be used to instantly spawn a Hidden Grotto around the player. This will only occur is the player is in Creative mode; if not, nothing will happen. The grotto spawner shares its inventory sprite with the Old Rod.
If you are using Sponge you will need the permission node pixelmon.grottospawner.use