That's way outdated - neither are N'Zoth's successes any longer. Neptulon already took the Kraken as pet during the encounter in TotT, we just didn't get to see it. Additionally, Yogg was the first one responsible for the Nightmare, he allowed C'Thun & N'Zoth access. N'Zoth is the only one responsible for the Nightmare now because Yogg and C'Thun are dead.