Where to get a Soothe Bell for Type: Null

[DinoIsBad]

So I just caught Type: Null and it seems that not only do I need to give it max happiness, but also a soothe bell to evolve. I may have sold Soothe Bell after getting it from the woman in Obsidia ward's salon. Is there a way to get it again? Thanks in advance. 

[Rendolf]

You don't actually need the Soothe Bell for the evolution, the diagram you're looking at is probably just using it to signify friendship. That said, to my knowledge that's the only Soothe Bell in the game, so if you still want one to help with raising the friendship someone would have to trade it to you.