Hey there. First off, fantastic rom hack! I've been getting back into the Pokemon TCG mainly with retro Wotc stuff this past year or so. I played the english translation of TCG2 and loved it. Was so happy to find your rom hack using the Neo cards!
I can confirm the above. I playing the game on original hardware using a everdrive flashcart from Kritzz (not a 5x or 7x mind you, a earlier version from a few years ago now).
I'm using version 1.3 of your rom, and im playing the legacy version. I patched a USA version of the rom, MD5 checksum is: 219b2cc64e5a052003015d4bd4c622cd (which is this exact rom here:
https://datomatic.no-intro.org/index.php?page=show_record&s=47&n=0931)
I just started the game, got my starter deck, and went to the rock club to fight Matthew. It was on his first turn, he played a card then "Matthew is thinking...." happened and the game crashed. Sound froze and buttons unresponsive. Had to reset my GBC and have not had it happen since but I've only fought him twice at this point and done nothing else.
Also had another glitch happen, I played a Croconaw on my 3rd or 4th turn against Matthew, I went to use the Screech attack, on the coin flip screen the game shows Japanese text. I've attached photos for reference.