Due to its sky-high Special Attack and snowball potential due to Beast Boost, Blacephalon acts as a niche but very scary setup sweeper capable of breaking through defensive Pokemon like Celesteela and Slowking. Additionally, Blacephalon can use Z-Moves to break walls it normally wouldn't, allowing it to snowball with Beast Boost much faster. Bloom Doom gives Blacephalon much-needed coverage against would-be checks like Tyranitar and Swampert. Substitute can be used with Ghostium Z to easily set up without worrying about priority attacks like Aegislash's Shadow Sneak and Bisharp's Sucker Punch from stopping a sweep early, as well as preventing status from crippling it, while using Never-Ending Nightmare to safely get KOs that it normally wouldn't have, such as OHKOing Clefable, Mega Latias, and Mega Venusaur with Stealth Rock, all after a boost. The EV spread guarantees a Speed boost from Beast Boost, as well as being able to survive a unboosted Zen Headbutt from Mega Gallade and a Shadow Sneak from an Aegislash with 8 Attack EVs after Stealth Rock. Calm Mind Blacephalon is most useful on hyper offensive teams that appreciate its unmatched ability to sweep through a weakened team while being able to lure in and take a KO on Pokemon like Tyranitar, which Pokemon like Galarian Moltres and Iron Moth can capitalize on to sweep themselves. Even with its immense power, Blacephalon struggles to take KOs without a Calm Mind boost, so entry hazard support from hazard leads like Excadrill and Mew are useful for chipping its checks into range of its attacks. Excadrill in particular can also reliably remove hazards, which is amazing for Blacephalon, as its weakness to Stealth Rock can easily put it into range of attacks. Pokemon like Iron Crown and Iron Moth are also amazing teammates, as they can weaken shared checks like Mega Venusaur and Hippowdon for each other so one of them can clean up. It also struggles massively with other Pokemon that can reliably outspeed it before it stacks up any boosts like Zeraora, Keldeo, and Iron Boulder, so Pokemon that can reliably take care of these Pokemon like Aegislash, Serperior, and your own Iron Boulder are great partners.