I went ahead and wrote down the color scheme for this bike for each character. There are a total of twelve color schemes for it.
- Red: Red Mii, Shy Guy, Red Yoshi, Donkey Kong, Tanooki Mario, and boy Villager.
- Orange: Orange Mii, Orange Shy Guy, Orange Yoshi, Daisy, and Baby Daisy.
- Yellow: Yellow Mii, Yellow Yoshi, Yellow Shy Guy, Wario, and Lemmy.
- Dark Green: Green Mii, Green Shy Guy, Luigi, Baby Luigi, Koopa Troopa, and Iggy.
- Light Green: Light Green Mii, Yoshi, Lakitu, and Isabelle.
- Dark Blue: Blue Mii, Blue Shy Guy, Blue Yoshi, Toad, Waluigi, Ludwig, and Link.
- Light Blue: Light Blue Mii, Light Blue Yoshi, Light Blue Shy Guy, Rosalina, Baby Rosalina, and Larry.
- Purple: Purple Mii, Roy, and Wendy.
- Pink: Pink Mii, Pink Shy Guy, Pink Yoshi, Peach, Baby Peach, Toadette, and girl Villager.
- Black (with flames): Black Mii, Black Yoshi, Black Shy Guy, Metal Mario, Bowser, Morton, and Dry Bowser.
- White: White Mii, White Shy Guy, White Yoshi, Mario, and Baby Mario.
- Brown: Brown Mii, Pink Gold Peach, and Cat Peach.
Something about the colors
I just realized that the City Tripper colors are based on different designs seen in Animal Crossing games. These are the ones I figured out:
White: Red Zap clothes
Green: Jungle Camo design
Light green: I think this is Leaf design
Pink: Blossom design
Blue: Blue Flannel design
Light blue: Possibly Blue Argyle design, looks somewhat different however
Black: Flame design
Purple: Big Star design
Orange: Though not obvious, the circle below character emblem indicates Citrus design
Yellow: Mix of Checkered design and Yellow?
Red: Most likely just plain Red, like a Red Parasol