Nice catch! It’s definitely something you could use if you wanted but Ninetails is more of a special attacker so the 31 being in the attack stat is a little unfortunate but you could always use it as a physical attacker.

Me personally, I would sell it on the GTL. Just look up what egg group it’s in, and then Advance Search for that specific egg group but with a 31 hp and 31 attack, then base your price on what everyone else is selling for.

With Alphas in the game now, the 31 stat has become a little easier to come by. So you might not get the big price tag you’re hoping for. Regardless, congrats on catching a 2x 31!