I was hunting for a wild chansey a lady in SS said she would give you something good if you brought her one well, I eventually found one and I saw it was holding an oval stone and I'm not at all familiar with this particular stone could you list the Pokémon that evolve with it?
Oval stones aren't really evolution stones, you have to let a Pokemon hold it and level it up for it to evolve. Only Happiny evolve in to a Chansey with it.
Hope this helps!
The only Pokemon that can use the Oval Stone is a Happiny. Instead of using it, the Happiny has to hold the item then evolve.