Mega Pendant appears in 4 version groups since Generation VI, an Unused item in the Key Items pocket
PokéAPI item 786 of 2,223, Unused category, Key Items pocket
Effect, in PokéAPI's words
Mega Pendant: “Unused NPC Key Stone.”
Unused. This is Wally’s Key Stone in Omega Ruby and Alpha Sapphire, but it cannot be obtained by the player.
Games
Mega Pendant is listed in the text of 4 version groups, first in Generation VI
Game index by generation
IIIIIIIVVVIVIIVIIIIX
Named in
Sun and MoonUltra Sun and Ultra MoonLet's Go Pikachu and Let's Go EeveeSword and Shield