https://pokepast.es/e77d591225892356
Lead Mamo Offense utilizes a lot of the tier's premiere offensive threats (Palkia-Origin, Zacian-Hero, Arceus-Fire) in addition to a solid defensive backbone in Corviknight + Giratina-Altered.
The general playstyle typically involves forcing powerful trades early in the game to open critical defensive holes in your opponent's team that can then be exploited by the respective best offensive threat. The combination of Ice Shard + Oblivious makes Mamoswine one of the most consistent counters to Cyclizar (denying Shed Tail with Ice Shard, cannot be taunted) and powerful Earthquakes that can 2HKO all Magearna sets and bulky Dialga leads. Mamoswine additionally has favorable matchups into other hazard leads. Meowscarada is limited to a single turn it can set up hazards due to Icicle Crash + Ice Shard. Masquerain can get up webs versus Mamoswine, but cannot get a second attempt at setting webs later in the game due to Ice Shard. Notably, Oblivious also blocks Intimidate in this matchup. Landorus-Incarnate has a 93.8% of getting OHKOed by Ice Shard, and if it survives you can set Stealth Rocks to ensure it will faint on re-entry. Outside of the lead role, Mamoswine's STAB combination is really threatening to a lot of teams, so you can get more value out of Mamoswine's Focus Sash with very strong early and mid-game offensive pressure against common threats like Giratina-Altered, Amoongus, Dragonite, Garchomp, Gholdengo and Rillaboom, and Sneasler. For many other in-game scenarios, Focus Sash allows Mamoswine to force awkward trades for your opponent.
Palkia-Origin is a special wall breaker that can put a lot of pressure against most teams' defensive cores, this set in particular is using Substitute and Fire Blast, which main targets are Arceus-Grass, Rillaboom, and the occasional Amoongus. Substitute on the other hand lets you scout for switches and get free turns to attack.
Banded Zacian is pretty self-explanatory. An incredibly powerful wall breaker with Fairy STAB and coverage in the form of Close Combat for Steel types and Psychic Fangs specifically for Arceus-Poison in addition to being a backup Reflect/Light Screen/Aurora Veil clearer. Tera Blast Ground grants him another complementary STAB to break more things like Dialga, Eviolite Crocalor, Magearna, Gholdengo, Iron Moth, Arceus-Fire, Slowking Galar, and Volcarona while also being a good midground option to click against teams that otherwise can pivot around Zacian-Hero.
Arceus-Fire is a win condition and sweeper that can turn the table in a lot of situations. Swords Dance into tera normal Extreme Speed can OHKO most fast threats and Flare Blitz deals with most bulky mons that would survive an Extreme Speed. This set's flaws are evident as it gets hard-walled by Giratina-Altered and Dondozo, but once they've been removed or chipped enough it can break through and grab the sweep.
Physically defensive Corviknight has the job of taking opposing Zacian hits while also chipping it down with Rocky Helmet. Defog is really important especially since it supports the Stealth Rock weak Arceus-Fire as well as helping to preserve Mamoswine's Focus Sash. Finally, U-Turn is slotted to ensure that Corviknight does not lose momentum every time it hits the field.
Specially defensive Giratina-Altered is the team's phaser, helping against Espathra and other setup sweepers while also stacking some passive damage with stealth rock. Willo-wisp followed by a 130bp Hex help to cripple switches and spread even more passive damage, neutralizing Magearna's leftovers and giving Giratina a boost on it's main STAB. Rest is it's only form of recovery with the downside of leaving Giratina vulnerable for two turns, still isn't much of an issue considering it's insane defenses. The item of choice it's Heavy-Duty-Boots, ignoring hazards and keeping Giratina healthy to tank more hits.
Replays:
https://replay.pokemonshowdown.com/gen9ubersuu-2012416209
https://replay.pokemonshowdown.com/gen9ubersuu-2012429259
https://replay.pokemonshowdown.com/gen9ubersuu-2012430945
https://replay.pokemonshowdown.com/gen9ubersuu-2012430945
https://replay.pokemonshowdown.com/gen9ubersuu-2012434265
https://replay.pokemonshowdown.com/gen9ubersuu-2012439422
https://replay.pokemonshowdown.com/gen9ubersuu-2012441592-dz77wlvcvywbn81gvmymkxbsiwj08qspw
https://replay.pokemonshowdown.com/gen9ubersuu-2012443178
https://replay.pokemonshowdown.com/gen9ubersuu-2012448368
https://replay.pokemonshowdown.com/gen9ubersuu-2013875461-4xs9pzm73k8s41ljcsrijfdk8sayj8vpw