Human/Viltrumite Physiology: Mark is a Human/Viltrumite hybrid and this gives him access to Viltrumite powers. Because humans are biologically similar to Viltrumites, this gives Mark the potential to become as strong as any pure-blooded Viltrumite. As Mark pushes himself, he can become faster, stronger, and more durable than he was before. Because of his Viltrumite heritage, Mark has the following powers:
Invulnerability: Due to his Viltrumite heritage, Mark is virtually immune to any/all kind of damage. Only beings of similar strength can actually inflict damage on Mark or even pierce his skin.
Enhanced Healing Factor: Due to his Viltrumite heritage, Invincible is immune to all diseases, disorders, imperfections, and can heal and regenerate from any injuries, even those that would normally kill Humans. Depending on how severe his injuries are, some injuries he's sustained can heal from in weeks and others take longer. Like all Viltrumites he adapts to any bodily harm as he regenerates.
Decelerated Aging: Due to his Viltrumite heritage, Mark's aging process is slower than the average Human, as he gets older his aging process will exponentially slow down further, eventually he'll stop aging. Mark can potentially live for thousands of years and will still be in his physical prime .
Dominant Genetics: Due to to his Viltrumite heritage, Mark's human genetics were overridden when he was conceived, making him more pure-blooded Viltrumite like Anissa, than human. 
Class 100+. As long as Mark pushes himself, he will likely become stronger than he was previously.
Vulnerable Ears: In order to achieve flight, a Viltrumite's equilibrium must be balanced. This system is located in their ears and thus anything that disrupts their inner ear function can disrupt their flight. This does not include loud sounds, but much rather certain pitch pulses. It can cause Mark's ears to bleed and possibly kill him if down for too long. This weakness has only been demonstrated on his father, Mark Grayson, but it is implied that other Viltrumites share it.