Mattel does not possess trademark registrations for specific shades of pink, like other companies do for their signature colors. However, Mattel has maintained rights in the specific Pantone 219C shade of pink, which they consistently use on their products. They have successfully argued that this specific pink hue has gained distinctiveness over the years and functions as a trademark. While Mattel has not sought registration for its pink mark, it is possible for them to do so in the future. Policing the use of their pink mark is important to Mattel, even without formal registration. The pink mark is valuable to the Barbie brand and boosting its overall brand value.
https://www.thefashionlaw.com/barbie-pink-what-is-it-and-what-do-mattels-trademark-right-look-like/
https://www.thefashionlaw.com/barbie-pink-what-is-it-and-what-do-mattels-trademark-right-look-like/