A pink shirt matches gray pants and can keep the gray color from appearing bland. Brightly colored shirts such as turquoise can be paired with gray pants as well.
Since gray is a neutral color and a mixture of black and white, both bold and subtle shades match with gray. For instance, both lavender and aubergine shirts can be flattering when worn with gray pants. A black shirt with or without silver accents would match a pair of gray pants and can create a polished, professional look. Metallic shades such as rose gold are flattering with gray pants, as are light hues such as blush.