To which you might respond "who?"
Ome of the lesser-used Mythical Pokemon is getting a glow-up in December.
A new trailer for the Pokemon Legends: Z-A Mega Dimension DLC has revealed a Mega Evolution will be available for the mythical Zeraora. Originally released in 2017 as an Ultra Sun and Moon exclusive, Zeraora will remain a pure Electric-type Pokemon when Mega Evolved.
The introduction of Zeraora continues a trend began with Pokemon Legends: Arceus where mythicals were made available during the game (Arceus as part of the plot, Darkrai and Shaymin as save bonuses).