Namco Bandai is fortunate; when they make the various Super Robot Wars games (through their subsidiary, Banpresto), they don’t have to license most of the material. Sunrise (famed super robot anime studio (for certain definitions of famed, I guess)) is also one of their subsidiaries, and that drastically cuts down on what they have to license.
Super Robot Wars W was the first game in the franchise to be released on the Nintendo DS; it’s also the first game in the series in which all of the robots featured are from shows licensed (at least in part) in the US.
Bullet Striker is the main character’s theme; like all main characters in SRW games, he’s original and not from an existing property (enough games have been made for Banpresto to release so-called Original Generation games, which feature exclusively characters and super robots created for SRW games).