All right, so here is my take on it:
Toxapex is Fine.
Gliscor may benefit more from a Jolly Nature rather than an Adamant nature, especially when you run Swords Dance and Facade, since you don't really need an Adamant nature at that point. Without Jolly, Gliscor cannot out-speed:
315 / Terrakion / 108 / Neutral / 252 / 0
311 / Garchomp (Mega) / 92 / +Spe / 252 / 0
310 / Hawlucha / 118 / Neutral / 152 / 0
310 / Charizard (Mega-X), Volcarona / 100 / +Spe / 184 / 0
309 / Landorus-Therian / 91 / +Spe / 252 / 0
309 / Pinsir (Mega), Sharpedo (Mega) / 105 / Neutral / 252 / 0
306 / Porygon-Z, / 90 / +Spe / 252 / 0
305 / Nihilego / 103 / Neutral / 252 / 0
303 / Garchomp / 102 / Neutral / 252 / 0
302 / Excadrill / 88 / +Spe / 252 / 0
301 / Thundurus-Therian / 101 / Neutral / 252 / 0
299 / Charizard (Mega-X), Charizard (Mega-Y), Gardevoir (Mega), Medicham (Mega), Manaphy, Salamence, Victini, Volcarona / 100 / Neutral / 252 / 0
296 / Hawlucha / 118 / Neutral / 96 / 0
295 / Hydreigon / 98 / Neutral / 252 / 0
295 / Kingdra, Nidoking, Tapu Fini, / 85 / +Spe / 252 / 0
291 / Mimikyu / 96 / Neutral / 252 / 0
290 / Mew / 100 / +Spe / 112 / 0
290 / Suicune / 85 / +Spe / 232 / 0
Ferrothorn is often used as a counter to common physical threats rather than a suicide lead, especially since it gets KO'd by special moves easily. It can sap HP and stall better if it had Protect rather than Spikes. Power Whip often Hits some of Ferrothorn's Physical threats (and Greninja) harder than Gyro Ball, so you may consider that as well.
Air Slash isn't that great on Charizard. It benefits more from Hidden Power [Ice], Hidden Power [Ground], or Earthquake, especially with Heatran, Landorus-T, and Zygarde being common Pokémon in the meta.
Tapu Bulu can Benefit from many other moves than Nature's Madness. Bulk Up/Swords Dance Bulu is very threatening, so you might want to use those instead. If you use Bulk Up, you could Replace your Def and Attack EVs for SpD and Speed EVs (with a Careful/Jolly Nature) to bolster Setup and survival, but this does lower Bulu's physical switch viability if you choose to do so. You could also Give Tapu Bulu Superpower instead of Protect to deal with Celesteela better:
0 Atk Celesteela Heavy Slam (120 BP) vs. 252 HP / 252+ Def Tapu Bulu: 170-204 (49.4 - 59.3%) -- 21.5% chance to 2HKO after Leftovers recovery and Grassy Terrain recovery
0 Atk Celesteela Heavy Slam (120 BP) vs. 252 HP / 0 Def Tapu Bulu: 234-276 (68 - 80.2%) -- guaranteed 2HKO after Leftovers recovery and Grassy Terrain recovery
+2 0 Atk Tapu Bulu Superpower vs. 248 HP / 104+ Def Celesteela: 173-204 (43.5 - 51.3%) -- guaranteed 3HKO after Leftovers recovery
+2 0 Atk Tapu Bulu Superpower vs. 248 HP / 104+ Def Celesteela: 173-204 (43.5 - 51.3%) -- 64.5% chance to 2HKO after Stealth Rock and Leftovers recovery
Giving Tapu Bulu Fightium Z makes Bulu KO Celesteela Faster, but keeping Leftovers may be worth it (use Charizard to weaken/KO Celesteela).
If you don't use Ferrothorn as a Suicide, Defog may work Better than Rapid Spin (as there aren't great Rapid Spinners in OU besides Excadrill). I suggest Rotom-W as a defogger:
Rotom-Wash @ Leftovers
EVs: 252 HP / 4 SpA / 252 SpD
IVs: 0 Atk
- Hydro Pump
- Volt Switch
This set Supports the Specially defensive, specially offensive Hazard Remover you wanted. It cripples physical attackers with Will-O-Wisp, has Hydro Pump to threaten specially weak Pokémon, Heatran, and Landorus; and Volt Switch for Pivoting and hits Celesteela pretty hard (Will-O-Wisp also helps take care of Celesteela).
I'd say this team is pretty great, but just like most things, it can be improved. Best of luck to You!
Hope I Helped!