Roost Mega Charziard X is generally a nice early game breaker. I've always wanted to build this but never had the motivation to do lol.
Team description:
Charizard: Functions as the team's main breaker, taking advantage of passive teams to setup or just being a really nice setup mon during the early or late game.
Gholdengo: Supports the team with it's usual paraspam set. I've run Shuca Berry mainly to lure Great Tusk, Landorus-T and Garchomp with Make It Rain. MIR also helps vs Diancie.
Landorus-T: Speed control of the team. Helps with offensively pressuring Diancie, Garchomp, Heatran and Gholdengo.
Explosion is ran over Stone Edge to catch mons like Zamaezenta, M-Latios and Gliscor off-guard.
Toxapex: Toxapex helps with walling Charizard Y, M-Lopunny and Zamazenta. Fairly a standard set, but with Payapa berry to lure Tapu Lele, M-Medicham and M-Latios to get a toxic off.
Ferrothorn: Ferrothorn and Toxapex pair up extremely well defensively. Ferrothorn is pretty diverse imo, and other moves should be ran on it. It runs Body Press here mainly for luring Kingambit while also having the added benefit of hitting Kyurem. Thunder Wave is ran as a secondary option, helping Charizard have an easier time against faster threats.
Terapagos: Finally, I added Terapagos for a secondary removal option and a Specially oriented breaker. Modest terapagos is cool since you get to 2HKO Ghold with Earth Power, as well as hit Heatran. Also, it's ability makes of great use to revenge kill when a Setup mon goes out of hand.
Threats:
Latios: Latios always has good matchups into such teams with it's Lusture Purge + Mystical Fire set. The way you can probably play around it is with luring it with Toxapex, using Landorus in a mindful way, and using Terapagos if needed.
Garchomp: Swords Dance Garchomp sets in particular, is a tough MU. You can play around it with Terapagos, Landorus and Gholdengo.
Zapdos: Offensive Zapdos sets are really good into this since it always forces a switch into Landorus, Ferrothorn and Gholdengo. To beat it, you need to keep momentum up with making predicts often when needed.
Heatran: Last but not the least, Heatran with both it's offensive and defensiev sets always finds a way to break these teams. To comfortably beat it, you want to keep Toxapex healthy, and use Earth Power from Terapagos whenever it's in a range of a KO.
Hope you enjoy the team!