That ought to be "Krankheit Turtle". "Krankheit" is German for "sickness".
If you want to be slightly more correct, it would be "Krankheits-Turtle". And if you want to go all the way, "Krankheitsschildkröte". Or "Schildkröte der Krankheit", as in "Turtle of Sickness".
@SNCE
I know that i'm late as f, but anyway, i also thought that this is rather peculiar name for detoxify. So i checked the original, and it's really just katakana [ディスポイズン]. The only way it can be read is "dispoison"