Well, this is a surprise to see just waking up. O_O
Don't really have anything to add that people didn't already say. I'll comment on a few things:
Name. I'm guessing the person on twitter that
Hydrachomp mentioned is right with it being a combination of the Japanese word for "gear" and "machina". Now usually the translation team doesn't really touch the names of "debut"/Legendary Pokemon that much nowadays (Lucario, Zoroark, Jirachi, Manaphy, Shaymin, Victini, Diancie, Hoopa, Volcanion, etc.), at most maybe changing a few letters around so that its name makes sense in other languages. So I'm betting
D_what is closer with its English name probably being "Machiana". Personally if they also want the "gear" somewhere in there I'd slightly change it more to be "Machinear" (also getting in a pun for "engineer" and maybe even "ear" in there), but as stated above they usually don't make that drastic name changes (last bit of Zoroark's name is believed to have come from "aku" which is Japanese for evil).
Appearance. At first glance I also thought "Robot Diancie" (with a bit of Lilligant) but looking closer I can see it has enough differences to make it its own thing (mind you I can't quite place my finger on what thing besides "robot"). One thing bothering me a little that I think it looks maybe a bit overdesigned, like I don't mind the bottom of it looking like a Pokeb Ball (though the Poke Ball itself looks to be a recent invention the sigil of it seems to have existed throughout the ages, take the Foongus family for example) but the pattern on the side and the overall design of the middle/chest makes it start feeling more like a Digimon (also the markings on the head). It's not too overdesigned and of course I'll get used to it, but I don't know, it doesn't feel quite like a Pokemon (though it is just a stock image, I'm sure once I see it in other poses and animated I'll feel different, just now it looks bizarre and out of place). Also not quite sure what the ears are for, like they look like they may combine but I don't know into what, like did the people who make it just give it rabbit ears "just cause"?
Type. Well definitely Steel. If there's a secondary typing I'd say Fairy BUT I don't want them to start spamming Fairy Legendaries at us like the did with Dragon. I'll be perfectly fine with this thing being pure Steel, it's man made afterall (I mean the Golett family has a reason the were part Ghost, but I'm getting a sort of steampunk feeling from Magiana and this next movie in general so I'd say a "mystical" typing like Fairy wouldn't fit the tone). Not that I would have a problem with Steel/Fairy either, but it would be then be sort of competing with Mawile (and Mega Mawile) and we honesty need more pure Steel-types (5 generations later and we only have 5 pure Steel-types: Registeel, Klink family, and Mega Aggron (who starts as a Steel/Rock type)). Also it would show not all cutesy, fairy-like Pokemon will get the Fairy-type which would be good for design practices as it means the artist won't be limited.
Role. DHR-107 brings up an interesting point in what its role is. I'm going to agree its probably a caretaker or I'm more willing to bet a groundskeeper of some sort, like at least in the movie its made to keep the gears of the steampunk city maintained. Wouldn't be surprised if its bottom portion opens up to reveal it stores extra gears. Also the red/blue meter thing catches my eye making me wonder if it has a role, like it uses it to keep a check on the condition of things (though how it works we'll have to see, like does it need to keep the colors balanced or is one color bad and another good?).
Legendary. Another issue I'm having with it is will it be a Legendary. It looks like a Legendary, and I'm not saying that just because its a new Pokemon. Unlike Lucario and Zoroark who look like natural creatures, this thing it too robotic and overdesigned to not be a Legendary. Like I can't really see going to a place, like a factory or something, and start running into these things left and right. It looks like a very specifically made Pokemon, like I can see it sort of being the queen (or if we're going to go by robot/technological terms, administrator/manager) of groups of the Klink family. Also the movie is sort of making me think this, unless Volcanion is chasing after a runaway one it sounds like there's only one. Though had the movie even said there was multiple I'd still think its probably a Legendary or really rare Pokemon who's locations will be VERY selective (if its a Legendary it won't have to worry about that quite as much thus the designer can design it anyway they like).
Pokemon Z. So yeah, usually a completely new Pokemon means next main series game is a new gen. HOWEVER, I would note that they have started some incompatibility issues (for lack of a better word) between versions with the ORAS Mega Pokemon (and Primals and their moves). It's one step off from just making a new Pokemon for the third version altogether, so maybe they decided to do it (or at least experiment with it)? Also it is taking a long time for Pokemon Z/XY2 to come out and it could be they don't want to wait until after it to start releasing new Pokemon (gotta keep that merchandise flowing). Of course, with that mindset they could have just decided to go "f*** it" and start advertising the next gen meaning Magiana may not be completely available in Z/XY2 (maybe mentioned and seen, but usable?). And if they do decide to skip Z/XY2... well I'd think it would probably be considered the most lackluster and if not most disappointing generation (barring the release of RS remakes). XY and the Kalos region really need a third version to flesh it out more (and if they're sequels maybe even pick up on some open ended plot threads), and to end it early would make it feel like Pokemon hit the polygon ceiling and used XY to get out their growing pains much to the region/gen's misfortune.
So yeah, those are my thoughts for now. Oh, and before anyone brings it up:
*Compares the two* NOPE! Not yet, try again.