Ranking the Demon King's forms strongest to weakest (Nanatsu No Tazai)

1.) Full Power Demon King 'Complete Possession'

2.) Demon King Zeldris 2nd Form

3.) Purgatory Demon King

4.) Demon King Meliodas

5.) Demon King Zeldris 1st Form

Note: Demon King Mel refers to the Demon King when in control of Mel's body without interference

Purgatory Demon king coud be argued to be stronger than second form dk zel

purgatory DK got rekt by Emo Mel when the latter awakened his power. Emo Mel is weaker than Current Base Mel, who was pushed back by 2nd Form DK Zeldoris, and forced to use his demon mark

Demon King Youth>Purgatory Demon King=Demon King Zeldoris #2>Demon King Meliodas>>>Demon King Zeldoris #1

1. Prime DK

2. DK Meliodas (he has Meliodas's True Magic as well)

3. Complete DK Zeldris

4. Purgatory DK

5. Incomplete DK Zeldris