Void fits the two max colour category though they're technically my sona. Just white and black is their common theme.
Let's see all the very simple characters ^^. All characters with one or max two colors! Small details like the eyes don't count. It's fine if they have a different color.
Very white-ish blue with bluer tinted wings, besides the literally black & white monsters, so far she's one of the only non-b&w monsters with a simple one-two color scheme. Technically Dr. Zark is one color completely (if we don't count his nose) but he wears clothes with two other colors on him so I didn't know if that counts.
Manager Orange is just shades of orange like her name suggests fbbdb also w some tints of yellow for contrast!