1. Obtain the Odd Keystone: You find this in the "Lost Tower" on Route 215, accessible after defeating the Elite Four.
2. Gather 32 "Oddish" Pokemon: This is a bit misleading. You don't need the actual Oddish Pokemon. You can acquire 32 "Oddish" from trainers in various locations, even by trading for them. Some locations include:
* Route 205 - Some trainers have Oddish.
* Route 213 - Trainers with Oddish.
* Route 214 - You'll find Oddish here.
* Route 215 - Check the trainers for Oddish.
* Trading: You can trade for them with other players or use the Global Trade System (GTS).
3. Go to the "Turnback Cave" (Route 216): Once you have both the Odd Keystone and 32 "Oddish," head to the Turnback Cave.
4. Enter the Cave and head to the "Odd Keystone" Location: It's located at the back of the cave.
5. Place the Odd Keystone on the pedestal: This will trigger a battle against Spiritomb.
6. Defeat Spiritomb: Once you've defeated it, you can catch it using Poké Balls.
Important Notes:
* "Oddish" Trainers: The 32 "Oddish" needed don't have to be all captured by you. You can obtain them through trades or battles.
* Trading: If you're struggling to find the "Oddish" Pokemon, you can always trade with other players or use the GTS.
* Location: The Turnback Cave is only accessible after defeating the Elite Four.
* Unique Method: This is one of the more unique and complex ways to acquire a Pokémon in the game, making Spiritomb a highly sought-after Pokémon for collectors.
Let me know if you have any other questions!