Gigalith

Boasting decent stats, good abilities, and a shallow-yet-usable movepool, Gigalith is an anti-metagame Pokemon that can beat some common foes in the 1v1 metagame like special and Flyinium Z Dragonite, Mega Charizard X, Mega Charizard Y, and Porygon-Z. Its overall bulk lets it tank some hits like an Outrage from Mega Charizard X and special attacks like Solar Beam from Mega Charizard Y and, when further enhanced by Sand Stream, more powerful special attacks like Dragonium Z-boosted Draco Meteor from Dragonite, Draco Meteor from Naganadel, Shattered Psyche from boosted bulky Tapu Lele, and Hyper Beam from Mega Gardevoir. It also has access to setup moves like Curse and, more importantly, Laser Focus, which, in tandem with each other, let Gigalith beat bulkier threats like Mega Altaria and Noble Roar Kyurem. Its mono-Rock typing makes it less vulnerable to attacks from Grass-, Fighting-, and Steel-types that would threaten other prominent Rock-types, giving it a niche over Mega Tyranitar, Golem, and Mega Diancie. In spite of all this, Gigalith is weak offensively to common types in the 1v1 metagame like Steel, Ground, and Fighting. This puts it at a disadvantage against Pokemon like Magearna, Zygarde, and Kommo-o, which can set up against Gigalith and knock it out. Also, its subpar Speed means it can't beat fast Pokemon dependent on status moves to win, like Smeargle and Jumpluff. Without setting up, it lacks the offensive punch to KO bulkier Pokemon, so Taunt from Pokemon like Mega Gyarados effectively prevent Gigalith from setting up. This also leaves it unable to beat physically bulky Pokemon immune to critical hits, like Mega Slowbro and Type: Null. All this severely reduces its usability in favor of other Rock-type Pokemon like Mega Diancie and Terrakion.