>>65477852A) Lui, Roboco, Miko, Suisei, Chama, Ayame, Mio, Noel, Bae, Bijou, Mococo, Ao
B) Sora, Mel, Subaru, Pekora, Towa, Koyori, Kaela, Ina, Mumei, Fuwawa, Ririka
C) Aki, Matsuri, Okayu, Chloe, Ollie, Anya, Mori, IRyS, Kronii, Kanade, Hajime
I think the ones easiest to get confused by there at a glance are Matsuri (different hairstyle) and Kronii/Ao (same hair color, same eye color, similar hair length, similar color scheme for the clothes), the rest is all pretty obvious imo