Based on the provided information, the character "Blackii" refers to Umbreon in the "Eevee & Friends" animated short. Arriving late to Sylveon's party, this shy and mysterious Umbreon initially stays apart from the group. This distance leads Meowth to mistakenly believe Umbreon threatens Pikachu and the others, provoking an attack. Sylveon swiftly intervenes, blasting Meowth away.

Umbreon then unveils a surprise cosmic light show, prepared with friends Weavile, Gible, Gothita, Gothorita, and Gothitelle. Using its Psychic ability, Umbreon levitates objects, including watermelons, as part of the display. Other Eeveelutions join to enhance the spectacle, delighting everyone present. Following the show, Meowth apologizes to Umbreon and its friends for the misunderstanding. They share a feast together as reconciliation. The event concludes with Umbreon sleeping among the group of gathered Pokémon.