Marvel loves to use its villains in unexpected ways. Some of the weakest antagonists in the comics have been involved in narratives that have resulted in their powers, skills, and roles getting upgraded. They suddenly become much larger threats and essentially enter their "god mode." This is when they reach the height of their potential.
God mode can look very different for each villain, as their goals and use of those upgrades massively vary. Regardless, these villains got a taste of what it would be like to be in the higher leagues, and they certainly enjoyed it while challenging heroic teams like the Avengers or the X-Men. Many of these foes have not had that elevated status long-term though.
9 Phil Coulson
Phil Coulson wasn't initially designed to be an antagonist. The MCU-created S.H.I.E.L.D. agent has been on a long journey in the comics that ended in his death. Compared to other potential villains, Coulson doesn't boast any real powers of his own and his tactical genius doesn't surpass the likes of Nick Fury. But Coulson's cynical attitude upon his return to life changed his mindset.
During the Heroes Reborn event, Phil Coulson went full-on god mode. With the help of Mephisto and the Pandemonium Cube, Coulson was responsible for rewriting reality. He used a corrupt Squadron Supreme as the replacement for the Avengers. In this reality he even made himself President. But the Avengers naturally found a way to reverse the status quo, removing Coulson's power.
8 Norman Osborn
Norman Osborn has always utilized the powers of the Green Goblin. It's hard to argue that this version of Osborn is weak in any capacity. But strip away goblin mode and all that's left is a weak and vulnerable entrepreneur who relies on his financial resources to seem like a threat.
The Dark Reign event allowed Osborn to reach his unique god mode without suiting up as Green Goblin. Instead, he became Iron Patriot, commanded his own version of S.H.I.E.L.D., and even led the Dark Avengers. With a Cabal of villains by his side, Osborn was untouchable. Ironically, it was the deterioration of Osborn back into Green Goblin that partially led to his fall from grace.
7 Titania
Mary MacPherran has spent most of her career battling She-Hulk as the villain Titania. Although she is physically strong, in the circles she runs in she's a weaker villain. She rarely claims victory and is certainly a D-list character whose plots are both forgettable and unambitious.
Although Titania might not be a genuine physical threat to most of Marvel's heroes, that all changed in the Fear Itself event. MacPherran was one of the characters chosen to wield a hammer of immense power. Upon picking up the weapon she transformed into Skirn, Breaker of Men. She quite literally went into god mode alongside figures like The Thing and Absorbing Man.
6 Parker Robbins
Parker Robbins has always been a low-level thug. The character gained the mystical powers of a supernatural cloak he had stolen from a demon. But Robbins was often depicted as weak and pathetic, unable to truly tap into his potential. That changed with the Norn Stones.
During the Dark Reign event, The Hood began to run a gang of villains under the tutelage of Norman Osborn. He was gifted the Norn Stones, which were relics designed to boost his powers. He had never tasted such strength before and went into god mode. But the collapse of Osborn's empire resulted in Robbins losing everything he had built.
5 Jester
Multiple characters have suited up as Jester across the years and all of them have been weak and insignificant. The character is goofy at the best of times, with Jody Putt also giving in to the absurdity of the gimmick. But Putt was thrown a lifeline during Civil War.
Jody Putt's Jester was unleashed into the Thunderbolts program and was given everything he could possibly need to succeed as a superhero hunter. This is what god mode looks like for Jester, with his trademark gadgets at his disposal. With the help of Jack O'Lantern, Jester actually defeated Spider-Man and was on the verge of killing him. A last-minute save from Punisher led to Jester being shot dead, meaning he went out at the height of his career.
4 Arcade
Arcade is a manipulator, tech genius and a masterful tactician. But he certainly isn't powerful. He's weak and without his vast resources, he is absolutely nothing. Arcade has fluctuated between forgettable foe and god mode throughout his career. The villain thoroughly enjoys playing god and controlling Earth's heroes from a safe distance.
Arcade's creation of Murderworld is a perfect example of when the antagonist has reached his peak. These carefully designed games are full of traps and murderous scenarios that he forces competitors to survive. His twisted sense of humor has led to a vast imagination, full of potential situations to place his victims in. But if he cannot execute those plans he's of no true threat to the supers.
3 Malekith
Many readers might forget that Malekith is an incredibly intelligent villain. But the Thor foe isn't as strong as he might appear. Compared to the other juggernauts, deities, and monsters the Asgardians are used to facing, Malekith has never truly compared. He is always on the cusp of the next level but can never seem to make that all-important step.
Malekith the Accursed's reputation completely changed during the War of Realms event. Malekith entered his own god mode and became a threat to the safety of Midgard. Weaponizing the powerful Venom symbiote, Malekith proclaimed himself to be the Butcher of Thors. The narrative finally unleashed Malekith's darkness, but his defeat would force him to revert to his weaker stature.
2 Gorr
Gorr's corruption arc is one of the best in Marvel Comics. He started life as a weak and powerless alien, living on a barren world. Without his bloodlust for the gods, he likely would have died the same way his people had. But his quest to rip apart the very hierarchy of cosmic power allowed him to enter a god mode of his own.
With the use of the All-Black Necrosword, Gorr became the God Butcher. He traveled across realms and worlds, murdering immense beings of power as he went. It's rather ironic that he seemingly transcended into a deity-like status in his own right. Legends were made concerning the mercilessness and brutality of the beast that slayed gods. His resurrection somehow led to a terrifying increase in strength.
1 Turk Barrett
Turk Barrett is a largely unknown criminal that has been a comedic thorn in the side of street-level heroes for a while. He's a weak physical threat and his operations have been broken down countless times. He seems out of his depth in the supervillain world and his schemes are laughable.
But Turk Barrett turned things around when he entered his own god mode. Unexpectedly gifted with the Mind Stone, he used his newfound strength to begin to construct a small criminal empire. It's more power than he's ever felt before, and he finally rose up the ranks of the underworld, attempting to replace Kingpin. But Doctor Strange eventually retrieved the Stone and Turk reverted to his usual self.