Prop Case appears in 7 version groups since Generation V, a Gameplay item in the Key Items pocket
PokéAPI item 619 of 2,223, Gameplay category, Key Items pocket
Effect, in PokéAPI's words
Prop Case: “Stores props for the Pokémon Musical.”
Games
Prop Case is listed in the text of 7 version groups, first in Generation V
Game index by generation
IIIIIIIVVVIVIIVIIIIX
Named in
Black and WhiteBlack 2 and White 2X and YSun and MoonUltra Sun and Ultra MoonLet's Go Pikachu and Let's Go EeveeSword and Shield