What color will you wear since your prom partner is wearing light blue gown?

If your prom partner is wearing a light blue gown you have several options.

A dark blue suit with a pale blue or white shirt and a striped tie in shades of blue would make you a cohesive couple.

In a warmer climate a medium grey suit with a white shirt and pale blue tie will look good and be a bit cooler.

If the prom is a very formal event you only good choice is a black tuxedo. A black tux is designed to look good no almost every one and with almost every colour known to man.