I'm very skeptical about these "leaks" for a number of reasons but looking at it from a designers stand point there are a lot of elements that feel off. For starters these designs are incredibly cluttered when compared to other anime art concepts (see
Charizard X,
Tepig and
Mega Swampert as well as previous stuff others have linked) it focuses too much on the over all design rather than the elements.
For example in Rowlet's final evolution's design it has him posed wagging his finger, in other concepts this would focus on just his hand and not as much focus on showing off the torso (example
Sceptiles tree and
Greninja's Mouth). The pulled back retractable hood is also only shown in black and white and this seems a bit backwards in terms of what to show as a lot of emphasis has been put on a pose and not on a key feature of the design (namely the hood-less head). The usage of the sign on the tree branch also has me skeptical. Litten's final evo being included in a scene where Ash, random girl and Rowlet also seems to break tradition as does the usage of orange only to colour in his action scene. Poppilo's evo has the text following out of water that really seems out of place when looking at this as a design sheet. The text, while used in Tepig and other designs, seems more scattered and unfocused in these designs, especially the use of colour.
All in all there a lot of elements here that really feel less official to me and more emulated. I freely admit though as we are moving into a new season there could be a design change and that these could become the new norm but, besides the concept of
Sycamore, the more I compare these designs to other sheets the more out of place they feel. One other design point that really has me skeptical is Litten's evolution's fire wrestling belt. Its a unique placement and one of the elements of design I really like but when looking into past controversy with Pokemon designs (Jynx, Bellossom, Kadabra) one has to wonder if the Pokemon Company would be so daring as to give a design a fire crotch. I know that designs have moved on since those days, just look at what yokai watch got away with in
CheekSqueak, but I still feel this design is a bit to risque. I also feel that Poppilo's design seems to far from the start but then I said the same about Samurott when he was first shown.
At the end of the day we won't know till Nintendo announces it but honestly I wouldn't mind if these were our final designs (with exception to fire/fighting) though as it stands I'm currently unconvinced by these designs and just think that someone lucked out with timing about guessing a fire/poison design. I'm sure coro-coro will shed some light when it drops as to the credibility of these claims or at least give us more of an idea of what to expect.