Gliscor has been seen as one of the most controversial Pokemon in the competitive scene. However, Gliscor has never been seen as too much of a big issue, seeing as the base stat total is only 510 compared to the similar defensive flying competition. For example, Landorous Therian has 90 more points in stats with 600 in total. Yet, the legendary leader of the genie trio seems to have trouble keeping up. Why is such a Pokemon the best in the current generation dominated by high power hyper-offense and unpredictability?
We must first look at what separates the Gliscor of this generation to the last three generations where he was present. The biggest nerf of this generation is that he now has lost the recovery move of roost. This is no small nerf, as Gliscor commonly used the move to recover half his health. However, with this move gone, it is difficult for the flying scorpion to repeatedly take hits as much as he used to. One would think this would impact the Pokemon’s defensive capabilities, as one of the main roles of this Pokemon is to soak up strong resisted hits or to take chip damage that other Pokemon can’t recover.
Such a weakness is not as much of a problem as other defensive staples like Blissey having the Pokemon’s recovery nerf. The reason is that it also stays healthy through the ability of poison heal, which means that when the Pokemon is poisoned, rather than losing damage, it gains 1/8 of the Pokemon’s health upon each turn. This gives the Pokemon not only immunity to other forms of chip damage such as burns or poison, but it also increases double the amount that the item leftovers heals(which is already infamous for keeping Pokemon like Heatan and Landorous defensively solid). Combined with its solid typing with immunities to both electric and ground type attacks and neutrality to grass and rock, resistance to fighting and bug, and immunity to spikes, it makes for a pesky flying Pokemon to kill. This, along with the move protection to guarantee healing and be immune to damage that same turn, makes it a very obnoxious Pokemon to kill.
On the subjects of spikes and other hazards, this generation also gave it the other two main hazards, spikes, and toxic spikes. With the Pokemon already possessing great defensive utility, it can now find turns of the opponents’ passivity against Gliscor to set up layers of hazards, whether it be the guaranteed damage of rocks, the extra damage of spikes, or putting your opponents on a timer with toxic spikes. Gliscors’ unique ability to not only fly over both forms of spikes, yet also be a flying type neutral to stealth rocks, makes it resilient to opposing hazards while getting their own.
While there are plenty of other hazard stackers that work similarly, such as Ting-Lu and Garchomp, none has the reliable recovery that Gliscor has, nor are they immune to enemy spikes the same unique way Gliscor is. Gliscor also has the benefit of being a ground type that can set up toxic spikes, which is important as one of the most reliable ways to get rid of toxic spikes is to send a poison type in battle. However, poison types are weak to ground types, which Gliscor can threaten. The only other notable ground type with this attribute is Clodsire, which has a significantly weaker attack stat than Gliscor, making the Pokemon a lot more passive. 
Gliscor also has plenty of utility moves that other Pokemon do not have. For example, Gliscor still has toxic to cripple offensive switch-ins and set up sweepers, as well as making sure Gliscor can defeat other Pokemon in a game of attrition, Knock-Off to remove other Pokemon’s passive healings or immunity to hazards, U-Turn to pivot or even an offensive set with Swords Dance and Facade, which doubles in power if statused, like Gliscor is every time. Even the way you can customize Gliscor’s EVs, whether it is a more offensive setup with maxed-out speed and attack, or whether or not you would rather choose to make him specially defensive or physically defensive to take hits better, each Gliscor set has a unique set of checks that one must use to remove the pest.
The environment Gliscor is in affects the Pokemon as much as he does with his own attributes. One of the most impactful Pokemon this generation is a Pokemon named Gholdengo, a steel/ghost type with the unique ability to block defog. Defog is a move that is used to clear hazards on both sides and unlike the other removal options, does not have a way to get rid of hazards on their side completely. Gholdengo is already a top-tier Pokemon required for any hazard-based teams and wall-breaking abilities, so a Pokemon like Gliscor pairs perfectly with it, causing an oppressive, hazard-stacking defensive duo.
Gliscor was last seen in generation seven when Hidden Power Ice was a common coverage move. This move could be learned by every Pokemon in the game and was one of the best ways to keep it in check. However, while Gliscor was not in generation 8, generation 8 removed hidden power as a move. This seemed to be a change Pokemon will follow up on, as in generation 9, hidden power was nowhere to be seen as well. While some could argue terastilization would effectively be the same, that would require one Pokemon to change into an ice type just to kill it, making the kill on Gliscor too committal as terastilization often is supposed to win or lose you games. The lack of a common ice-type coverage move for most Pokemon only exaggerates how much worse removing the Pokemon can feel, as by the time you have removed it, it may have already been too late.
Gliscor has proven itself to be a strong contender in the OU metagame, maybe even a little too strong as it was voted to be banned on Nov 12, 2023. While one could argue for many reasons for a defensive Pokemon like Gliscor to be suffocating, others could argue the Pokemon brought defensive stability in an undeniably power crept generation. Either way, Gliscor has proven itself to not only come back with its competitive consistency but to be so talented in the metagame to get itself banned.
