Mega Archopy X
Grass/Dragon
Levitate
Sp. Atk focused
Mega Archopy Y
Grass/Flying
Aerilate
Speed focused
@umbramatic drawing their design for a Mega version of Archopy, my alternate Grovyle evolution, made me both want to draw it myself and also to properly hash out my own ideas for a Mega Archopy that I'd vaguely had rattling around in my head. Conveniently, their theme is “Archopy, but pointier”, whereas my idea had always been the opposite: “Archopy, but smoother” - so the two can coexist without overlap. Archopy gets to have two Mega forms, then, because why shouldn't it?
Umbra going for the more mythological-based Quetzalcoatl-inspired approach with their design, which I have deemed Mega Archopy X, made me think a Dragon typing would be a good fit. Plus Levitate, because it wouldn't be Archopy if it couldn't fly, but with wing leaves that spiky, it seems more like it'd be flying through some mystical draconic power rather than by any laws of aerodynamics.
My design for Mega Archopy Y takes some vague inspiration from Mega Salamence's theme of just leaning extra-hard into the WIIIINGS, as well as also bringing it a bit closer to an actual archaeopteryx. Still Flying type, of course, and now with Aerilate too, to really ram that typing home.
Both Mega Archopy forms would be much better fliers, with greater aerial mobility and able to stay airborne pretty much indefinitely without needing rest, unlike regular Archopy. On the flip side, though, they'd both be less mobile on land, Mega Archopy X because its legs are shorter in this more snakelike form, and Mega Archopy Y because all that extra wing surface area kind of gets in the way while running. The temporary Mega forms may be good for flying, and for extra power, but they're not practical to stay in all of the time.