You can play the game with a full English translation. The translation was originally started by a group known as "The Hero's 11" and later continued/picked up by other community members. While early versions required complex patching processes, the modern method is much more accessible.
The "Supernova" team is exclusive to its namesake version. Inazuma Eleven Go Galaxy Supernova English Patch
You must own a legitimate copy of Inazuma Eleven GO Galaxy: Supernova (the Japanese cartridge or a legal digital dump) to apply this patch. Piracy is not condoned. The patch is a modification tool. You can play the game with a full English translation
After years of waiting, what is it like to finally play Galaxy in English? Inazuma Eleven Go Galaxy Supernova English Patch
Galaxy shakes up the formula in two major ways.