I’m not exactly sure how many of each were distributed but the Dialga vs Palkia Stadium card is a lot rarer then the Mew vs Celebi Championship Arena as the Mew vs Celebi card was distributed in both english and japanese while the Dialga vs Palkia Stadium card was only available in japanese
I understand that noone knows exactly how many were distributed. But would anyone want to risk a guess, based on what you know about the size of the Japanese Battle Road events? 200, 1000 or 5000 copies? Or more?