Grab an Eevee at the Joyous Tower (floor 12 to 17). Increase its IQ to four stars with white and orange gummies (check Mount Steel for these items). Once you do that, use the lunar or sun ribbon on this guy in the Evolve Cave.

The lunar ribbon is in Northwind Field, floor 20. You will need the associated key to this dungeon to access the item.

The sun ribbon is in Wavern Hill. You will need an associated key for this item.