^ In regards to Leviathan Dragon, I wouldn't be surprised if that was Shark's unlock reward as opposed to Shark Drake. In a similar fashion to how you got Junk Warrior with Yusei instead of Stardust Dragon.
Let's be honest here Aleister could've come at any moment and in any world, Aleister has no relation with the dsod movie. The only slightly relation is that he is a spellcaster and if that was the reason he could have come when Carly became unlockable as well