Nintendo has announced that they are showing a new Direct tomorrow. This Direct will run for eight minutes, and be solely focused on Pokémon titles.
No other information has been given about the contents of the Direct. The most likely reveal will be the rumored Pokémon Stars, which is said to be the third game in the Alola generation. Pokémon Stars is rumored to be on the Nintendo Switch, which would make it the first mainline Pokémon game to appear on a home console. The recent announcement of a Switch version of Monster Hunter XX makes the idea of Pokémon Stars more plausible, as Capcom are releasing an upscaled 3DS game on the Switch. If Pokémon Stars is real, then it likely won't look much better than Pokémon Sun & Moon, as Nintendo haven't had the time to create something fresh for the Switch.
There is also the possibility of a Nintendo Switch port of Pokkén Tournament. A Japanese gaming blog recently reported that an arcade stick was coming to the Switch and that it would be compatible with Pokkén Tournament. This post was quickly rewritten, with all mentions of Pokkén Tournament omitted. A deluxe edition of Pokkén Tournament with extra characters would be a good fit for the Switch, as the portable nature and handheld format of the console makes it a great choice for competitive gaming.
Pokémon Go may also make an appearance during the Direct. The game has seen a significant drop in its user base, which Nintendo and Niantic will be eager to win back. Pokémon Go has lots of room for improvement and a major update to the game is the kind of thing that would be saved for a Direct.
Nintendo has a history of not holding back their big Pokémon reveals for E3. They would rather save their announcements for features in CoroCoro magazine than use them during the biggest gaming press event of the year. This is tied into Nintendo's marketing strategy of giving new updates through Nintendo Directs that run throughout the year, rather than bunching them in with the reveals made by Sony and Microsoft. Could this be a bullish attempt to gather as much publicity as possible before the white noise of E3?
The Pokémon Direct can be found here on June 6th. It will run 7:00 a.m. PT/10:00 a.m. ET in America and 15:00 BST in Europe.