Darth Krayt (pre-rebirth) vs Darth Wyyrlok

this is Krayt towards the end of legacy (prior to being reborn) vs Darth Wyrlokk

who would win?

"His [Wyyrlok's] knowledge of the rituals and and lore of the Sith is unparalleled, and his dark side abilities are surpassed only by Krayt."
--Star Wars Insider 88

Krayt wins.

Arguable.

Before his re birth I'd say Wyyrlock could win the force battle as there force powers were a stalemate when Krayt was reborn if I'm correct. With that his rituals also helping I'd say Wyyrlock could win.

They really weren't stalemating in the Krayt vs Wyyrlok fight but I do think Krayt's fear of his parasites overcoming him could be his downfall against Wyyrlok. Reborn Krayt was completely healed and had overcome his fear of being consumed so he shrugged off Wyyrlok's assault. He was able to get through what Andeddu did to him too, but Wyyrlok is a different beast who knows everything about Krayt.