He was referenced during the DP Arc.
Palmer holds a meeting of Frontier Brains.
He meets Platinum.
He is then reunited with his son, Pearl, and the two of them battle Darkrai; however, Pearl doesn't get an attack in because Palmer defeats Darkrai handily, using Cresselia's Psycho Shift to turn Darkrai's Hypnosis against it. Pearl then tells Palmer of Diamond's death, shocking Palmer, but Diamond arrives and reveals he survived.
- Psycho Shift
- Aqua Ring