Are you ready to see way, way too many Capcom, Namco, and Sega characters in the same place? Namco Bandai accommodates that desire with this sixteen-minute Project X Zone trailer.
In addition to a really cool animated opening, this video shows pretty much every aspect of gameplay, and then introduces all the characters by series. It's quite thorough. Even the characters from Resonance of Fate show up! Look for them after the humiliating KOS-MOS fanservice.