I can't think of a way to say it better than Capcom's Seth Killian said on the Unity Blog. Just when you think Tatsunoko vs Capcom: Ultimate All-Stars is out of surprises, you get something new. Recently it was an entirely new Tatsunoko character: Yatterman No.2. This time it's a shmup! (That's short for shootem-up)
Tatsunoko vs Capcom: Ultimate All-Shooters is one of the many mini-games that will be present inside the game. It's a 2D shmup similar to Capcom's own classic, "Commando". It takes place on the arctic wastelands of Lost Planet, pitting you against legions of Akrid bugs.
The game has four playable characters: Ryu and PTX-40A from Capcom and Ken the Eagle and Tekkaman from Tatsunoko. Each character has its own specific regular and special attacks and movement. The game even has mini-bosses, bosses, and branching paths! You can also play 4-player co-op! It's like getting a free XBLA or PSN downloadable title for free with the game!
Tatsunoko vs Capcom: Ultimate All-Stars his the Nintendo Wii on 26 January. Plan to pick it up!
Source: Capcom Unity