Shiny Pokémon are the scarce variant of the original Pokémon. They have a distinct shine around them and unusual color to them. You can catch these unique Pokémon in Pokémon Go, but they’re challenging to encounter. You have a low chance of it happening, and there are always techniques to try and enhance. Unfortunately, those seeking out a Slugma shiny version, this Pokémon does not have a shiny version at the time of this writing. Slugma does not have a shiny version yet, but it should reveal in a later event.
The developers behind Niantic typically release this Pokémon type variant alongside one of their weekly events. For example, during Weather Week in the Season of Legends, Castform’s rainy day form received a shiny variant, and all players have an increased chance of finding it in the wild. Even then, the odds were stacked against players, and they always will be when it comes to finding a shiny Pokémon.
Slugma will receive a shiny form sometime in the future, though. All of the Pokémon from the Kanto region received theirs during the Tour: Kanto event at the end of the Season of Celebration.
Slugma is a decent Pokémon, as is its evolved form, Magcargo. Some players have attempted using it in the Ultra League, but it’s a little tricky, and it’s a niche Pokémon, so it doesn’t always take off. It even struggles in the Great League. Given its overall stats and moves, you have better Fire-type Pokémon options to fight against your opponents.