Good colors that go with grey are light colors. like a yellow or light blue or light pink or light green.
I'd say black.
Many!! basically every color. It's pretty difficult to go wrong.
A neon color, or purple
black whaite and gray.
purple goes best
GRAY
Other greens, browns, and gray.
Probably a gray coat.
White
Gray is probably the best.
Black goes good with everything.
Pale colors such as medium aqua or lavender. You could check a color wheel to see what colors would coordinate with yellow and gray.