The unnamed trainer is a character appearing in Pokémon: DP Battle Dimension.
Pokémon the Series: Diamond and Pearl
He left his Lickitung in care at Angie's place. When the trainer decided to pay another visit at the day care, Angie apologized to him for evolving his Pokémon. Instead of being angry, the trainer was actually happy that his Lickitung evolved into Lickilicky because that was his plan overall when he left his Lickitung at Angie's place.