Mmm, it feels good to upload regularly. I should do that more often, huh? Well, at least it would feel good if I stopped getting these blasted "unknown errors" x_x.
Info: This battle is unlocked AFTER you beat Ninetails on Oni Island (along with many other bead quests). The Kusa 8 rematch pits you against 3 rounds of Canine Warriors without a break in between. Not particularly difficult, but hoarding items is helpful since they can knick off a lot of damage and are harder than their original fights. First round is Chi (Japanese Spitz), Shin (Boxer), Rei (English Pointer), and Ko (Collie). Then for some reason Gi (Siberian Husky), Chu (Kai Ken), and Jin (Shiba Inu) return for round 2, but might not be them and only replacements or something. And last but not least, we of course have Tei (Tosa Inu). All the dogs have their original attacks, as well as some additional ones that are shared (ex. digging) or completely new (ex. THE BATTOUGA!). And my question has been answered. You CAN fight them if you started a new game and you got the bead on a previous playthrough.