Hi Fence, welcome to the forum. It's not so much Hydreigon is not available but getting is consider illegal. Thw reason why because, it requires 3 dark materials and a soul candle to get deino but there's only 2 dark materials currently in the game so, getting a 3rd one requires you to eithet cheat or trade one from someone who has one. Hopefully u have a good time here the people here are pretty friendly.