First answer about colours worn by Yokai-Indy

The red mask worn by Omnikai draws attention to himself and gives a sense of evil. The white on the mask creates wonder and confusion. The black gown makes him mysterious and anonymous to his enemies. The red Omnikai's mask that he wears after the incident of Tadashi is used to automatically draw attention to himself when Hiro first runs into him when he tries to find where his microbot is leading him to. The red is used to automatically hit the audience with the feeling of evil within Yūkai. Also not knowing who is behind the mask at first, this also makes the audience know of his power. The white on the mask also strikes a bright appearance to the audience, striking them with a feeling of wonder and confusion. Wondering who the person behind the mask may be or what his intentions are, the black gown that Yūkai wears makes him seem very mysterious and anonymous to his enemies.