Before I watched playing Splattack in Squid beats 2, but I thought it doesn't exit in Squid beats 2. How do I play it? (I'm a Japanese player, so if the gamemode's name is incorrect, please edit this post)
All 8 songs from the first Splatoon game in Squid Beats 2 (including Splattack!.) are Amiibo exclusive. Splattack! specifically is gained when scanning the original boy inkling Amiibo from the first game. Each of the other original songs are acquired through the other original Amiibos. Hope this helps.