Why is Gackt (yes, that's him) appearing in an article about a Gundam game?

Because Gackt is Gundam! Behold, Extreme Gundam:

Extreme Gundam is the boss you face off against in Gundam Extreme VS's single player mode. It's actually pilotless, but within it rests ex-, a bodyless core that believes the world's history to be one of despair, full of mistakes and sadness, and longs to create an ideal space with its own hands.

The ex- core is voiced by Gackt.

You'll get a shot at taking out Gackt when Gundam Exteme VS hits arcades tomorrow.