There are few things the Hulk cannot smash, but Thor’s Destroyer was one of them as the Destroyer armor is a mystical weapon created by Odin himself which contains the raw, unparalleled power of the gods. However, in one particular battle, the Destroyer revealed a single weakness to the Hulk specifically, and Hulk used that to defeat a weapon that was originally built to kill Celestials.
The Destroyer is an autonomous suit of armor made from Uru metal–the same substance used to forge Mjolnir–and is enchanted by Odin, which only added to its physical invulnerability. As for attacks, the Destroyer is super strong, fast, and can project beams of extremely powerful cosmic energy of all sorts including intense heat, plasma, and even anti-matter. The Destroyer was created by Odin after he and the other elder gods of the cosmos, including Zeus and Vishnu, became fearful of the vast power exhibited by the Celestials. So, Odin thought it wise to create an unkillable warrior of destruction–putting everything he had into forging the perfect cosmic destroyer.
In Incredible Hulk #461 by Peter David and David Brewer, Bruce Banner has returned from an alternate future where an evil version of the Hulk known as Maestro ruled the world with an iron, tyrannical fist. However, when Banner initially escaped from that world he wasn’t able to go straight home, but instead ended up in Hell alongside Maestro where their conflict raged in perdition. Once Banner found his way out of Hell, he finally arrived back in his original time, though he didn’t return alone. Maestro was also able to claw his way out of Hell and enter Bruce’s reality, though when he did so he was in an incredibly weakened state, making it highly unlikely that he’d be able to beat the Hulk one on one. However, Maestro found a way to possess the Destroyer and immediately became one of the deadliest villains the Hulk had ever faced–or so he thought.
When Maestro attacked the Hulk as the Destroyer, the semi-sentient armor became confused as it couldn’t tell the Hulk’s spirit apart from the one that was possessing it. Since the Hulk and Maestro are technically the same person but from different points in time, the Hulk was able to enter the Destroyer without any trouble as the Destroyer registered both of them as the same entity. The Hulk kicked Maestro out of the armor after using its confusion to his advantage and defeated Maestro with his superior strength.
While the Hulk would more than likely lose against the Destroyer if it was intent on killing him since there is no way Hulk would be able to smash its enchanted Uru armor while also taking an insane amount of damage from its god-tier attacks. However, since the Destroyer was merely being controlled by an alternate version of himself, the Hulk was able to beat Thor’s Destroyer after discovering a single weakness unique to this particular fight alone.