Not A Bug Pokémon from same base species can mega evolve

[RyukTheDarkrai]

What type of bug are you reporting? Mechanics

What is the bug?
Galarian Slowbro is capable of Mega Evolving in National Dex and other non-Legends ZA metas where the Slowbronite is legal

Are you able to replicate it? If so, how?
giving Galarian Slowbro a Slowbronite and allowing it to Mega Evolve in battle

 

[Hydrametr0nice]

That's how it works. In gens 6 and 7, Mega Charizard X can evolve to Mega Charizard Y with Charizardite Y.

If in future games (not counting Legends Z-A) this is no longer the case, we will updated it.