Marshadow separates itself from other common picks with reliable and hard-hitting STAB options with unresisted coverage. Its great Speed tier allows it to outpace Mega Rayquaza and Arceus, while its Fighting typing, immunity to Extreme Speed, and ability to steal stat boosts allow it to revenge kill Swords Dance Arceus formes and check some Calm Mind sweepers. A fantastic ability in Technician also enables it to boost the power of moves such as Rock Tomb, Shadow Sneak, Hidden Power Ice, and Pursuit, while a 195-Base Power STAB Z-Move allows it to break through bulky defenders, stall, and balance. Spectral Thief is an amazing STAB move, due to the prevalence of boosting moves in the metagame, that allows Marshadow to be a great weapon against hyper offense. Furthermore, a great priority move in Shadow Sneak helps Marshadow threaten faster Pokemon such as Ultra Necrozma and Mega Gengar, while Bulk Up allows it to be a frighteningly powerful wallbreaker after a boost. Marshadow also has the potential to serve as an excellent revenge killer against offensive teams with correct prediction, but it struggles to break defensive walls it can't hit super effectively. Marshadow also suffers from having poor defensive utility, meaning it can't switch into many of the Pokemon it checks, and is weak to common threats, such as Arceus-Fairy and Yveltal, both of which threaten it out with their respective STAB options. Because of its middling Attack stat, it can be walled by Pokemon such as Arceus-Poison, Primal Groudon, and Zygarde.
Using Marshadow requires a lot of skill, and it's not easy to spam, beat 'em all Pokemon. On the other hand, its speed isn't too bad. 383 at max isn't pretty low.
It has Spectral Thief, but is very frail and is outsped by Calyrex-Shadow and Zacian-Crowned and many more.
Yes, but it shouldn't be forgotten that Calyrex-Shadow is always OHKOed by Shadow Sneak, along with many things like Ultra Necrozma with Life Orb, making it valuable. Spectral Thief is an a-m-a-z-i-n-g move which means boosting stats infront of Marshadow means you're pretty much forfeiting.
It can also deal with Xerneas (i.e. survive Moonblast with Focus Sash, steal the boosts then have a team member revenge kill it).
Some handy calculations
- 252 Atk Technician Marshadow Shadow Sneak vs. 0 HP / 0 Def Calyrex-Shadow: 460-544 (134.8 - 159.5%) -- guaranteed OHKO
- 252 Atk Technician Marshadow Pursuit vs. 0 HP / 0 Def Calyrex-Shadow: 308-364 (90.3 - 106.7%) -- 37.5% chance to OHKO
If they gonna switch, they are trapped. But, if they Dynamax Calyrex-S and set-up Psychic Terrain, then Marshadow loses if it uses Shadow Sneak.
- 252 Atk Technician Marshadow Shadow Sneak vs. 0 HP / 0 Def Dynamax Calyrex-Shadow: 460-544 (67.4 - 79.7%) -- guaranteed 2HKO
- +1 252 Atk Marshadow Spectral Thief vs. 0 HP / 4 Def Zacian-Crowned: 190-225 (58.4 - 69.2%) -- guaranteed 2HKO
- After stealing the boosts, if it clicks Shadow Sneak:
+1 252 Atk Technician Marshadow Shadow Sneak vs. 0 HP / 4 Def Zacian-Crowned: 127-150 (39 - 46.1%) -- guaranteed OHKO at 30% which is the maximum damage output.
VS Ultra Necrozma
- 252 Atk Marshadow Spectral Thief vs. 28 HP / 8 Def Necrozma-Ultra: 290-344 (84.7 - 100.5%) -- 6.3% chance to OHKO
(It carries 28 HP/8 Def to survive Shadow Sneak from Life Orb at full HP)
Just don't forget one thing, status boosting meta can be nowhere seen in non-Hyper offense, meaning Marshadow struggles to defeat bulky Pokemon against which it doesn't have super effective moves.
Marshadow struggles to break bulkier Pokemon, so wait to play it until those foes are weakened down enough. Marshadow should also be used as a capable revenge killer, taking out important threats like Dragon Dance Mega Rayquaza and checking Arceus formes such as Arceus-Dark and Arceus-Steel.
As such, Marshadow is only limited to a revenge killer and can only be used against Hyper Offensive teams, Bulky and stall teams it cannot break, especially when there's our Primal Groudon and Arceus-Fairy, and it's capabilities are now here that of Yveltal's and Calyrex-S' wall breaking strength.
Hope this helps!