Pokémon in Pokémon Go are constantly changing, with some receiving a buff that benefits them in mobile play. Most of the time, if a Pokémon's stats are okay, it comes down to their move set and the attacks they can learn. Attack pools are limited for each character, so if a Pokémon doesn't have the best attacks, you can expect to see a rework in the future. This is what happened with Cofagrigus at the start of Battle League Season 9. So with a little tweak, Cofagrigus is good and how can you best use it in Pokémon Go?
Cofagrigus is a Ghost-type Pokémon. It will be weak against Dark and Ghost-type moves, but is resistant to Bug, Fighting, Normal, and Poison-type moves. When using Cofagrigus in PvP, it has a maximum CP of 2.273, an attack of 140, a defense of 199, and a stamina of 131. If you are using it in PvE battles, it has a maximum CP of 2.570, an attack of 163, defense of 237 and resistance of 151.
The stats on Cofagrigus are decent. It is a bulky Pokémon with a higher defense than attack, but it can do enough damage to outlive most Pokémon in Great or Ultra mode. Unfortunately it will not be to compete in the Master League. If you want to use it in PvP, it can compete in both Great and Ultra. However, if you plan to use it in the Ultra League, it will be much better if it has access to XL Candy.
The most important thing holding Cofagrigus back was the Pokémon's quick move pool. Previously, it only had a striking and zen headbutt, two of the worst fast moves in Pokémon Go. However, at the launch of Battle League Season 9, Niantic added fast-moving shadow claw to its pool, greatly increasing its utility and we highly recommend using it in these competitions.
If you've wanted to experience Cofagrigus on your team, it's a great Pokémon to use in the Grand and Ultra Leagues. It will be best used as the main Pokémon, so it will be the first Pokémon you will use in a battle. With the fast-moving shadow claw, he can build up energy fast enough to use his charged quick moves, putting a good amount of shield pressure on most opponents. With no shadow claw, Cofagrigus is a mess and you don't want to use it.