So look at the stats first, Mega Delta’s stats line up w/ Mega Y’s. Also the ability, Noctem, is a weather ability, like drought. the typing dragon also adds more charizard x. (although that goes through the whole line so, i might be wrong here, also this is the only element to the stats charizard x adds)
Now for the looks:
the mega delta has a long horn going back, kinda like mega y. (this could possibly be wrong though because y has two smaller horns near it, also this is the only element i could find that charizard y applies to the looks[besides the orange on the shiny, that the whole line except mega x has]) now charizard x has these arm horns and so does mega delta. the wings are also very similar, and the eyes have fire coming out of them just like the fire coming out of mega x’s mouth (may not be true but is there).
EDIT: @Steelman2004 said the hands are the same for charizard x and mega delta which reminded me that the pose both of them are making are the same. (they might’ve used mega x for the sprite before adding a more ghostly feel)
Side Note: This not part of the fusion but, mega delta actually has a tail. see that floating flame, if you look under it it actually looks like a tail. (my perspective changed for a second and i suddenly saw a tail lol)
I can see a lot of similarities thanks to you pointing it out. Like simply compare the hands of Delta and X. They’re the same. And I’d be willing to bet the eyes on Delta are a combination of the flames you pointed out and Y’s extra horns.
what? the tail thing? i just noticed the tail thing today but, the rest i realized after seeing them both (while i was looking at the graphics folder lol)
the wings are also very similar, and the eyes have fire coming out of them just like the fire coming out of mega x’s mouth (may not be true but is there).
emoji. Mostly.