The chance to catch Pokémon Go's Spiritomb works pretty similarly to the game's Mythical Pokémon, that were also caught through Special Research tasks - but Spiritomb is unique, in that it's the first non-Mythical Pokémon to be caught in this way.
The game's first non-Mythical Special Research Pokémon is available as part of a Special Research quest named A Spooky Message, where players must complete a series of objectives as part of a story-based questline.
How Spiritomb quest 'A Spooky Message' works in Pokémon Go
As part of a March 2018 update, Pokémon Go introduced new Research quests, where players complete objectives for special rewards.
There are two types of these quests - Field Research and Special Research. It's this latter type we'll be focusing on, as where Field Research offers objectives that can be collected by players at any time, Special Research is a story-driven questline with specific steps.
Spiritomb's Special Research quest is named 'A Spooky Message', and will see you Professor Willow take on some particularly spooky challenges, just in time for Halloween.
At at the end? Players will be given Spiritomb, of course, as a reward for its completion - just like Mew and Celebi before it.
The quest is broken down into just three stages this time, with a few challenges to complete per stage, and rewards to be unlocked as you go, too.
Though there is no A Spooky Message end date - once you start the quest, you can take as long as you like - if you haven't already started it, you have to do so by November 1st at 9pm UK time (1pm PST) to add it to your quest list.
Though these are similar to Field Research quests, the specific steps are fixed for every player - so if you don't mind spoilers, you can plan ahead and learn what you need to do to complete them all catch Spiritomb.
Otherwise, there are no restrictions on how fast you can complete A Spooky Message, so provided you fulfil the criteria of each stage, Spiritomb could be yours in no time at all. That said, though there's no 'difficult' steps, a few might take you some time to complete!
How to complete each of Spiritomb's 'A Spooky Message' quest steps
Here are all three steps and their rewards in A Spooky Message. Be wary of spoilers before continuing, if you are worried about learning what each objective entails before unlocking them.
'A Spooky Message' Step 1 of 3
Rewards for completing Step 1: 10x Poké Ball, 1080x Stardust, 8x Silver Pinap Berry
Note - A quick and easy way to complete this step is being able to use a Berry on a Pokémon, but then not catch them, which still counts towards your total!
'A Spooky Message' Step 2 of 3
Rewards for completing Step 2: 10x Poké Balls, 1080x Stardust, 8x Silver Pinap Berry
'A Spooky Message' Step 3 of 3
Rewards for completing Step 3: 18x Spiritomb Candy, 1080 Stardust.
Spiritomb stats and what else you need to know about Spiritomb in Pokémon Go
Spiritomb is an unusual Pokémon, featuring one of the most challenging catch methods in the main series games Pokémon Diamond, Pearl and Platinum, and originally having no weaknesses to any types at all.
Now however, it does have one weakness - the more recently-introduced Fairy-type - but it still has the double-resistance to Normal and Fighting-type attacks in Pokémon Go, and a resistance to Poison, too.