Apart from Mega Victreebel, the August 21 Pokemon Legends Z-A trailer featured a host of other pocket monsters. There are no reveals of new Pokemon among these, with the video solely focusing on the destructive (yet playful?) nature of the Mega Evolved form of Victreebel.
Based on the media we have seen so far, we have some idea of what the Pokemon Legends Z-A Pokedex will look like. While The Pokemon Company has released details on two new Mega Evolutions, they have remained tight-lipped regarding whether there will be any new regional variants.
Pokemon Legends Z-A Mega Victreebel reveal trailer: Full Pokemon list

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The following Pokemon appear in the "The Case of the Sweet Scent Incident" YouTube video (in the order of their appearance):
- Scatterbug
- Sableye
- Espurr
- Spinarak
- Noibat
- Mega Victreebel
A Clefairy stuffed toy can be seen early on in the clip once the two humans enter the building. If we missed any other appearances, do drop a comment below mentioning the same.
The setting of the video is a dilapidated, deserted building. The two people we see in the footage are investigating the place regarding a sweet scent that emanates at night. The aforementioned Pokemon appear at different points as they make their way through the corridors and up the stairs.

They finally come across a room with its lights on. A trainer bursts out of there before Mega Victreebel crashes through the wall. The two investigators are seen scrambling downstairs and out of the building. By the end of the clip, Mega Victreebel changed to Victreebel and seems quite happy with the mess it has made.
Has The Pokemon Company announced any new Pokemon for Pokemon Legends Z-A?
No, there has been no new Pokemon species confirmed for Pokemon Legends Z-A. For now, the developers have confirmed Mega Dragonite and Mega Victreebel as two new Mega Evolution forms debuting in the upcoming title.
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