Wirlm colour:

a) Feeding it a turnip changes its color to purple
b) Feeding it a water lily seed changes its color to red
c) Feeding it a watercress seed changes its color to green

Yellow Mousemallow:

If you feed a Mousemallow a piece of cheese, it will turn yellow

Yellow Shellybean:

If you give a Shellybean corn it will turn yellow, To get the shellybean to turn green, get it to eat a gooseberry.
For a shellybean to turn blue, have it eat a bluebell.

Yellow Syrupent:

Give your Syrupent a Buttercup and it will turn yellow!

Red Badgesicle:

When you feed a badgesicle an apple it will turn red

Pink Maccaroon:

Feed a maccaroon a water lily seed (not flower)

Light Purple Mallowolf:

Direct a mallowolf to a blackberry so it will eat it. It will then turn very light purple, almost a pinkish color.

Flutterscotch:

Firstly you'll need a white Flutterscotch. Here's which flower makes which color Flutterscotch:
poppy -> red
bird of paradise -> orange
buttercup -> yellow
watercress -> green
bluebell -> blue
thistle -> purple
water lily -> pink
tulip -> black
bullrush -> brown .

Horstatio:

Bluebell, turns blue, watercrest seed turns green, chilli turns red.

Lickatoad:

Give a lickatoad an apple and it will turn red.

The Aracknit colors are blue bell flower, jack'o'lantern, or a water lily flower.
The Bunnycomb colors are goose berry, pumkin, or a water lily flower.
The Goobaa colors are blue bell flower, tulip seed, water lily seed.
Newtgat colors are bird-of-paradise, water lily seed, blue bell flower.