BU LO Wallbreaker for Gen 8 Anything Goes
Marshadow @ Life Orb
Ability: Technician
EVs: 252 Atk / 4 Def / 252 Spe
Jolly Nature / Adamant Nature
- Bulk Up
- Poltergeist / Spectral Thief
- Shadow Sneak
- Close Combat
Gen 8 saw the removal of a sizeable majority of Pokemon that checked or countered Marshadow, such as defensive FairyCeus, PoisonCeus, WaterCeus, Primal Groudon, etc. which were capable of greatly hindering Marshadow's wallbreaking capabilities.
While Marshadow lost access to its Z-Move, it also gained a stronger Ghost-type STAB in Poltergeist as well as the ability to Dynamax that lets it break past the sturdiest of walls conveniently. The removal of Arceus from the game as well as defensive cores being centered around Yveltal, Eternatus and Necrozma-Dusk Mane made Marshadow one of the most threatening wallbreakers present in the entire tier. It also acts an offensive revenge killer to the omnipresent Calyrex-Shadow.
Bulk Up sacrifices instant firepower and coverage in return for boosting Marshadow's already good Attack and letting it set up on passive Pokemon like Tyranitar, Necrozma-DM, Chansey/Blissey, Ferrothorn, etc. It especially works well in conjunction with Dynamax, letting Marshadow 2HKO/OHKO almost everything after a single Bulk Up.
Poltergeist is chosen over Spectral Thief in most cases as the increase in base power lets Marshadow achieve 2HKO on targets that Spectral Thief would fail to. Notably, Poltergeist 2HKOes Eternatus which the latter fails to do so. You should generally be using Ditto as a reverse sweeper anyway, but Spectral Thief has its uses in hitting itemless Pokemon like Air Balloon Xerneas, Sitrus Berry Eternatus after their items are consumed. It also discourages Pokemon like Zygarde from setting up Coil on it.
Shadow Sneak is a strong Technician boosted priority boosted, for faster targets like Calyrex-Shadow which would otherwise KO Marshadow first. It also revenge kills heavily chipped Pokemon like Xerneas, DD Necrozma-DM, DD Zekrom, Groudon, Zacian-C, Scarf Kyogre, etc.
Close Combat is Marshadow's best available Fighting-type STAB, which hits Ghost-resistant Pokemon hard. A combination of Fighting and Ghost type moves have almost perfect coverage, which is a part of what makes Marshadow so scary to face.
A Jolly Nature is preferred as it lets Marshadow outspeed standard defensive Eternatus sets which would otherwise outspeed and click Recover on it, though Adamant can also be used when paired with Thunder Wave support from Kyogre, Ho-Oh, etc.
Calculations:
> 252 Atk Life Orb Marshadow Poltergeist vs. 164 HP / 0 Def Eternatus: 238-281 (51.5 - 60.8%) -- 91.8% chance to 2HKO after Black Sludge recovery
252 Atk Life Orb Marshadow Spectral Thief vs. 164 HP / 0 Def Eternatus: 195-230 (42.2 - 49.7%) -- guaranteed 3HKO after Black Sludge recovery
252+ Atk Life Orb Marshadow Poltergeist vs. 248 HP / 208+ Def Ho-Oh: 200-238 (48.1 - 57.3%) -- 92.6% chance to 2HKO
252 Atk Life Orb Marshadow Poltergeist vs. 248 HP / 208+ Def Ho-Oh: 183-216 (44 - 52%) -- 14.8% chance to 2HKO
+1 252+ Atk Life Orb Marshadow Max Phantasm (140 BP) vs. 248 HP / 208+ Def Ho-Oh: 382-450 (92 - 108.4%) -- 50% chance to OHKO
+1 252 Atk Life Orb Marshadow Max Phantasm (140 BP) vs. 248 HP / 208+ Def Ho-Oh: 348-411 (83.8 - 99%) -- guaranteed 2HKO
+1 252 Atk Life Orb Marshadow Max Phantasm (140 BP) vs. 252 HP / 252+ Def Prism Armor Necrozma-Dusk-Mane: 398-468 (100 - 117.5%) -- guaranteed OHKO
+1 252 Atk Life Orb Marshadow Close Combat vs. 248 HP / 0 Def Yveltal: 387-458 (85 - 100.6%) -- 6.3% chance to OHKO
+1 252+ Atk Life Orb Marshadow Close Combat vs. 248 HP / 0 Def Yveltal: 426-503 (93.6 - 110.5%) -- 62.5% chance to OHKO
Teammates:
Calyrex-Shadow and Marshadow form a great offensive core, with each being able to threaten the other's respective checks. Marshadow takes cares of special walls like Yveltal, Chansey, Tyranitar, etc. for Calyrex-Shadow as well as revenging Ditto transformed into Calyrex-S. In return, Calyrex-Shadow pressures Xerneas, Eternatus, Zygarde, Zygarde etc. which annoy Marshadow well. Both can also overwhelm their shared check Ho-Oh with their sheer offense. Meanwhile, Xerneas and Zacian-C also appreciate Marshadow dealing with Necrozma-DM and support Marshadow by being Yveltal switch-ins. Cleric Xerneas can extend Marshadow's longevity by cleansing status and acts as a good wall to Yveltal, Zygarde-C and other Marshadow. Kyogre and Ho-Oh can bait Eternatus without Thunder Wave, thus letting Marshadow break past it much easier. They can also tank hits from other Ho-Oh on Marshadow's behalf.