True Devil Kazuya is when Kazuya absorbs the powers of Azazel, and not only can fly and fire powerful lasers, he can even control crystallines. True Devil Kazuya is powerful enough to defeat gods.
Shinnok can corrupt life forces in his modern form and is twice as powerful when in his corrupted form. But his divine power as an Elder God makes him twice as powerful than his corrupted form.
Mortal Kombat is the strangest universe when it comes to character strength but I would put Base Shinnok pretty close to Cetrion who can be bigger than earth and as for Corrupted Shinnok should be even stronger