There is not unfortunately. The IVs are simply put, terrible.
If you have the time, you could consider restarting the game. Then, when you are at the story's climax and have to engage Yveltal in a battle, use a Pokemon with Synchronize and check its IVs after you captured it. Softreset if the IVs aren't to your liking. Alternatively, you could sell your soul to someone who has a Power Save and have that person edit the Yveltal with Black Magic.
Either way. I am genuinely sorry for your loss.
If you have the time, you could consider restarting the game. Then, when you are at the story's climax and have to engage Yveltal in a battle, use a Pokemon with Synchronize and check its IVs after you captured it. Softreset if the IVs aren't to your liking. Alternatively, you could sell your soul to someone who has a Power Save and have that person edit the Yveltal with Black Magic.
Either way. I am genuinely sorry for your loss.
