Warning: Spoilers for season 1 of Invincible ahead.
Season 1, episode 8 of Invincible features a battle between Invincible and Omni-Man for the season finale that ends with Omni-Man's retreat, but which one of them is really more powerful? With Omni-Man turning from the world's greatest defender to the world's greatest threat, it seems Invincible is the only one who can stop him, but can he really? Mark's powers have been growing exponentially, but defeating Omni-Man isn't an easy task.
Mark and Nolan are both Viltrumites, an advanced species from out in the stars. Viltrumites have abilities that humans don't—they can fly, have superhuman strength, and showcase greater endurance, speed, and agility. Episode 8 of Invincible revealed that the Viltrumites are attempting to take over the universe, one planet at a time, and Mark may be the only one who can stop them. Mark has only recently come into his Viltrumite abilities, so defeating Omni-Man may sound impossible, but both Mark and Nolan have their weaknesses.
In their episode 8 fight, Omni-Man is the clear winner; there's no match when it comes to brute strength. However, episode 8 also proves that Mark can endure an incredible amount, more than anyone else could and even more than seen in previous episodes. In his past encounters, Mark has struggled with some of the bigger villains throughout Invincible — particularly Battle Beast. However, Omni-Man is able to punch a hole through The Immortal and tear him into two. In their training, it's clear that Omni-Man is still faster than Invincible, as Mark has quickly been adapting through Nolan's teaching. Mark does get improved strength when he gets angry, but his experience with big villains shows his strength isn't on par with Nolan's yet. Omni-Man is considered the quintessential superhero — he's hit with a 400 billion dollar satellite weapon and walks away with a nose bleed. Defeating Omni-Man is going to be no easy feat.
Mark's weaknesses are a little easier to spot. He's had his powers for a brief time and has a fraction of the experience Nolan has under his belt, and it's his inexperience that is his greatest weakness. Invincible is impulsive and sometimes quick to anger, but he also carries a great empathy for those he loves and those he's sworn to protect. Mark feels incredible guilt when it comes to the loss of human life, and there is plenty in episode 8, whereas Nolan views them as disposable while not hesitating to take advantage of Mark's weakness. Omni-Man has his own weaknesses with shedding his morals, and though he claims not to care for Mark and Debbie, the fact that he leaves instead of finishing Mark off proves that his son is likely his greatest weakness. Nolan is also overconfident, and his arrogance may cause him to underestimate his enemy and leave himself open for a fatal blow.
But Mark has a major strength on his side that Omni-Man no longer has; Mark has allies and plenty of them. The interference of the Guardians of the Globe could be what Mark needs to overpower Omni-Man. In a one-on-one encounter, Omni-Man would likely win. If he and Invincible come to blows again, it's a great possibility that the Guardians' intervention is what will push Mark into a victory (especially since the Guardians now know what Omni-Man has done to their predecessors). His previous encounter with the original Guardians almost leads to his death, so their addition to the fight could mean the end for him. In the world of Invincible, Omni-Man now stands alone, which just might be his greatest weakness in the end.