it is exactly 1 base point faster, rock type, adaptability power gems OHKO no doubt, gets a better protect I really don't see why not?
In short yes it is.
If you want a longer answer this is for you. Mega Glimora is a great counter not only to char Y but to Char Y teams. Sludge bomb lets you kill Floette/Slyveon and Whimsicott all of which are common on Char Y teams. Spiky shield can chip Basc into range of an attack from other one of your Pokemon. Earth power can kill Kingambit another common Char Y team member. The only Pokemon Glimora can’t kill on Char Y teams is Garchomp but you can just have another one of your Pokemon kill Chomp.
