The trailer shows that the selection of Pokémon you can play as has been greatly increased since Pokémon Mystery Dungeon: Gates to Infinity. The Direct also revealed that the game will be released in Japan in September.
A new Nintendo Direct was shown off in Japan today and included the first footage for Pokémon Super Mystery Dungeon. While the trailer didn't show off too much of note it did reveal that the plot will likely be heavily focused around legendary Pokémon. The trailer can be viewed below: