Go to correct place in correct room in the Sea Mauville. Press "A" until the battle starts. If it's not shiny (which it won't be) soft reset. If by some magical stroke of luck it is shiny, USE TAUNT BEFORE IT USES MEMEMTO!!!!!!!!!!! Spam Poké balls until it stays in one. *insert it's been 3000 years meme or do the thing you see to you*
Ignore the the instructions... unluess you actually want to shiny hunt it (you don't). I drew the Spiritomb. The pictures for memento and taunt came from Bulbapedia. The paper, shiny charm, shiny mew, and Sea Mauville photos all came from Google Images. The music is from here: https://www.youtube.com/watch?v=ELd8kkCOt88 Also, I meant to share this yesterday morning, not Sunday evening.