I was like "is it on the poster??? Is it a seperate form altogether?!?! WHAT IS THIS??? WHERE IS IT???"
As for split starter forms...
Like I said I don't think it's safe to say confirmed, but I do think them more likely than before. Just for pure speculation fun, if there are separate forms, I think that Poppliovely and Liften is the night form as many have said, but I kind if think Rowlet3 is the day form... He just strikes me as a daytime creature with his hood...like he's using it to keep the sun out of his eyes and wouldn't need it at night.
Just because they leaked together, if there are seperate forms, doesn't mean they are the same ones necessarily. We still don't know who leaked them, how they got them, where they got them from, etc... To leak this kind of information so early is difficult to begin with, it was likely some third or even fourth party that had access to it via someone else who has limited info from someone else, etc. But all this is just my thoughts. Doesn't mean it's true or anything, just what to think based on what I see. There are still some people who think Nintendo themselves leaked the concept art as part of their hype and build up to the games.
If there are split forms, I think they will still keep similar themes (performer, long range attacker) but that they do have potential to branch off more than expected. I think Rockruff's evo forms have rather large differences between the forms for being the same Pokémon and shows what we can expect. Different stance, colour scheme, highlights, etc. Perhaps the other Rowlett3 has feather daggers, and fights closer up with kicks and wielding his dagger, but also can throw the daggers from a distance if need be. Maybe he's bulkier than the archer to handle those up close hits and is heavierz thus loosing his ability to fly and gaining a second type ( like grass/dark or something). This is what I mean by different but similar enough... Like the idea lines up with his first form still, but doesn't differ far in concept from the archer whilst having a different angle/spin.
This isn't to fuel the whole qudraped Litten thing. I'm not trying to build false hope. We don't even know if we will get split forms. But, I could see changes being made that mirror Rockruffs.