Here's how it looks animation wise:
It even appeared in the wild for a brief period of time today:
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Shortly after, Pokemon Go's Head of Marketing, Kenta Suga, left this tweet about it:
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So despite this new Pokemon turning into a Ditto in the end and vanishing from people's games, it looks like this was a marketing ploy on Pokemon Go's part.
The dataminer from yesterday also found out that this Pokemon has an ID of #891. This is likely referring to its number in the National Dex, and it could imply that we're getting at least 84 new Pokemon for Generation 8. We don't know whether this could be a Mythical Pokemon or the first stage of an entire evolution chain though.