I'm planning to make a Nostalgic Kumos, and I read that Vanya asks for one of multiple kits. I just wanted to make sure that if I give him the Nostalgic Kumos, I will always have to get the Plushie Makers Kit (since the pet is a plushie and all) because if he doesn't, I'd rather not spend 4 million on the kit.

Yes, the Plushie Makers Kit will always be asked for plushie like Nostalgic pet. Each nostalgic instruction have one of 4 (maybe 3 not sue anymore) that is always asked depending of the specie and two random ones. You will also need a Essence Of Melody to give life (per say) to your toy.

c: Alright, thank you.