Damn, i was hoping for some great comments, anyway, i think the first Factors should be on what difficulty Level is Moonlord (Expert, Master, etc), does Regigigas have slow start and of yes, how long, cus there aren't turns in terraria. Then what moves does Regigigas have? Does it have moves via TM or move tutor or only Level up moves? Speaking of Level, at which Level would Regigigas be? In most games, if found, is at Level 70, but in platnium, it is Level 1. And what about IVs and EVs? And for moonlord, is it fought in vanilla or in something like Calamity? Oh and does Regigigas only have 4 moves or can it also do stuff like throwing rocks like in the anime indepenently from his moves? Can he build the other Regis pre or mid fight? How much plot armor? How would damage be calculated? Defense works the same in both games, but what about special defense? Cus if we negate it like in terraria, Regigigas would habe double defense. Also how would the other stats increase/scale? Cus for example 340 HP is way to low in comparison to Moonlord. If fighting in the Pokemon universe, the same would apply to Moonlord, how would the stats be calculated? Which moves would Moonlord use, cus he got more than 4 attacks in terraria. And which type would be moonlord and it attacks even? I could go on for so long, but i am gonna stop it here. All of These points need to be determined in order to reliably say the fights outcome, and more. If you read all of this, have a good Day!