Black Gate Keys are required to Duel him at the Gate.
He appears in-game after the player reaches Stage 6 of Duel World (5D's), at which point his Character Unlock Missions become available. Prior to November 24, 2021, he could only be unlocked in the special eventRaid Duel - Fear the Meklord Emperor!. Prior to being made available as a playable character, he appeared as an opponent during the event Primo is here!.
As one of the three Emperors of Iliaster, Primo aimed to rewrite the present to prevent a post-apocalyptic future. That required the complete destruction of New Domino City, which he was more than willing to do with his army of Duel Bots and his powerful "Meklord Emperor Wisel".
When starting a Duel with Yusei Fudo, Primo announces "I'm the one who will strike you down, Yusei Fudo!" or "When I defeat you, I'll snatch your Stardust Dragon!"
When he wins the Duel, Primo says "Synchro is far too great for a pest like you to wield!" followed by "You have failed, just like your Father!" or "Vanish along with the world, Yusei!"
When he loses the Duel, Primo says "Yusei Fudo, I will get my revenge!"
Aporia, Paradox
When starting a Duel with Aporia or Paradox, Primo announces "Don't order me around! I do whatever I want!"
When he wins the Duel, Primo says "Hahahaha! Look at that! You lost!"
When he loses the Duel, Primo says "Humph... Fine."
Card-specific
When Primo activates the effect of "Meklord Emperor Wisel" in his hand, he announces "An effect destroyed my monster, so I Special Summon this!" or "I use Meklord Emperor Wisel's effect to Special Summon it!" When Primo summons "Meklord Emperor Wisel" (by any method), a cut-in frame of Primo briefly appears and he announces "Do you feel a dark shadow of doom closing around you? It's the shadow cast by my Meklord Emperor Wisel!" or "Combine into one! Meklord Emperor Wisel!" If "Meklord Emperor Wisel" has not been previously summoned in the current Duel, an animation of "Meklord Emperor Wisel" being summoned plays afterward.
Most of the time when Primo attacks with that monster, he announces "Meklord Emperor Wisel! Attack! Stainless Steel Slash!"
When Primo activates that monster's Ignition Effect, he announces "Meklord Emperor Wisel absorbs your Synchro Monster!" or "Your Synchro Monster will fuel my Meklord's strength! Synchro Absorption!"
When Primo activates that monster's Quick Effect, he announces "Meklord Emperor Wisel negates and destroys your Spell!"