I have never seen Vilgax in Space Suit when he appear in outer space. In movie Ben 10 and Secret of the Omnitrix, he appeared in vacuum multiple times.
Assuming he is a powerful creature whose body can ignore pressure difference between vacuum and atmosphere (even laser blasters don't affect his body), how can he live without oxygen or something similar for respiration? I have seen gazillions of Sci-Fi canons, but never found a single living organism which could live without respiration.
Is there any information of his species regarding this? How does his body produce energy without respiration?