Cofagrigus is pretty bad in monotype
Cofagrigus (M) @ Leftovers
Trait: Mummy
EVs: 252 HP / 4 Def / 252 SAtk
Quiet Nature (+SAtk, -Spd)
- Shadow Ball
- Hidden Power [Fighting]
- Trick Room
- Nasty Plot
The classic OTR cofagrigus can be forced out by multiple pokemon on almost any stall or balance team, and powercreep since XY makes it even harder to use against the offensive teams it shines against than it used too. This is it's most popular set for a variety of reasons. It's best matchups are ones where ghost already has the advantage, such as against fighting teams so I find it iffy nowadays.
Cofagrigus @ Leftovers
Ability: Mummy
EVs: 248 HP / 252 Def / 8 SpD
Bold Nature
- Will-O-Wisp
- Shadow Ball
- Pain Split
- Curse / haze / toxic spikes
Facing competition from dusclops, a bulky cofagrigus had some appeal as a physical wall last gen, but nowadays, gourgeist super can boast similiar bulk, a reliable healing in synthesis, a typing that is superior given the partners avaialbe (ground,water,electric resist, aegislash for brave bird and chandelure/jellicent for fire pokemon) Cofagrius is seldom worth the effort.
However, Curse, makes cofagrigus much more interesting, as it is now both a wall tank and a stallbreaker, as anything with a 3HKO or worse will take a full 50% damage if they stay in to kill cofag, and switching out to remove curse allows a maximum damage painsplit. This is a massive weapon in the vs flying, and vs normal matchups, and still sees limited use against teams ranging from stall water to poison. Because ghost itself is a stally type, having an attack that goes through substitute, magic bounce, and puts most setup sweepers into ko range of priorty (including protect/king's shield) can salvage games. However curse is risky due to it cutting cofag's own HP, and without this gamble move it is very easy to sit him out. Taunt shuts cofag down completely, although it is not particularly common in the monotype meta. However, most fat pokemon with recovery can shut his non-curse sets down just as easily, and most of them dominate their respective usage lists. Toxic spikes also works as a kind of anti-stall meausre, but the teams most likely to run stall will have immunity or overwhelmingly effective defoggers. Against offensive teams it can prevent crucial will o wisps on offensive threats.
Cofagrigus's mummy ability is nice for forcing switches against people who can't touch you when they lose their guts, huge power, tough claws, etc, but the coffin pokemon lacks momentum against the fierce teams that are used nowadays. It's other stall attacks include infestation and magic coat. It's leftovers item is more a catch all, and it can be personalized to anything from kee berry to mental herb, depending on which specific counters you want to be able to catch off guard. Like other pokemon with monstrous physical defense, you can run an awful crocune set if you want too as well, which arguably frees up your megasableye to be used for something else.
It's limited to ghost teams in monotype, and it's clear from a distance that it's movepool and typing aren't up to snuff, but if you do pick him, his raw stats in its high defense, acceptable special, and bad HP (for a more effectice painsplit) can put in significant work against opponets who won't know what to expect from something with such abysmal usage.