Still up to speculation, since the lore is very messy and inconsistent at this point, but my power ranking would be:

S-tier: Dark Unk, Goblin Unk, Cleetus, Beast Mode Unk

A-tier: Debt Unk, TJAC (when he covers Original), Top Hat Unk, Unk while speaking of the importance of the enviroment

B-tier: Fedora Unk, Unk (while defending Shay)

C: The actual Unkle Adams (no shapeshifting or boosts), Unkle Adams but spelled with a C (Uncle Adams)

D: Unk while buffed by Brian Glow's magical tricks (not actual magic)

E: Unk while bulliying the Needle Drop (Needledick Unk), Nunavut Unk (dumb and easy to trick, but has freezing powers)