Here is a link showing off all of Drago's abilities for every single form he has taken.
From the looks of it, even Base Drago had Power Nullification and the ability to sap strength from others. Also, that Aquas Ability he used as Infinity Drago also counts as Power Nullification and Power Stealing (Think Ban from Nanatsu No Taizai with his Snatch ability). However, I can side with the idea of transmutation for that ability card as well.
Cross Drago can reflect attacks of seemingly any attribute, and there isn't too much else that's new. In all fairness, a lot of the forms share the same types of hax, but there are some forms that have unique abilities, like Helix Drago being able to increase his speed through the use of Dragon Hummer.
As for the hax of Perfect Drago, any feat displayed by Silent Naga or Wavern should be applicable to him as well, as he gained both of their powers and should then have all of their hax. As for Infinity Drago, any feat of the Infinity Core that was displayed while owned by Wavern, like bringing the dead back to life and healing the sick, as well as allwoing plantlife to grow again.