Meltan:
So it is a Mythical, interesting. As
Siggu said, even when compared to the previous "cute" Mythicals it still looks out of place. It looks too simple; it's a gray Ditto with a copper bolt for a head, floating pupil, and stripped wire tail. It looks like a basic stage Pokemon, making me think there has to be something additional to it like another evolution step (we got Legendaries and Ultra Beasts that evolve, why not a Mythical?) or it has another form (be it just something that needs to be triggered or a Mega/Ultra Evolution).
Pure Steel-typing a bit of a surprise as it's mentioned it generates electricity by absorbing metal into its body. But hey, we kind of need more pure Steel-types and it's not the first Steel (or Rock) that's able to generate electricity but not be Electric-type (Nosepass family, Klink family).
Quickly going over the reveal trailer, first it's a cute idea; I like having the Professor's talking with each other. That said, BOY do the art styles clash, lol. Also, Willow, you sound way too young to have white hair (or is that suppose to be your natural hair color?).
Second, um, it's an ancient Pokemon? The Pokemon with an industrial produced bolt head and a wire tail with modern day insulated wire covering... is from an ancient culture that wrote on stone tablets? And it's not like it got these extra features now, the ancient tablet shows it with these features already! GF, come on, in the past you went out of you way to explain why certain Pokemon like the Klink family and Magearna were both mechanical and ancient, but I think this is stretching it. Like maybe I could have bought it having the bolt head, but the wire tail? Unless you're going to introduce one of those lost ancient cultures that had high technology these just seems like lazy writing.
Cross Gen Evo-lacking:
I think them not having any more cross gen evolutions had to factor in how they handled Gen V and VI. Since Gen V took place in a region based on one outside of Japan they wanted to emphasize this by having the first initial paired games not have any older gen Pokemon during the main game, thus no reason for their to be cross gen evolutions (even though Alomomola should have been a Luvdisc evolution...). Then Gen VI introduced Mega Evolutions and GF's logic was probably "why have a plain ol' evolution when we could give it a suped up Mega Evolution". What
Codraroll suggested with them not wanting to "demote" a probably popular Pokemon to just being another stage is also probably a good reason (though I'd also think they would welcome this previous fully evolved Pokemon now being able to use Eviolite, and they still have the original Pokemon if they don't like the evolution; in that light a Mega Evolution is kind of worse to have as they don't get the Eviolite bonus and some probably now require their Mega Evo (which you can only have one on your team) to be considered useful...).
Putting in new Evolutions also has the not-cool side effect of messing with National Pokedex order
The Pokedex ordering kind of needs a redo anyway, a set-up where if they add a new evolution or form they won't need to re-number all the Pokemon.