When the groom wears a pink shirt, he can consider wearing a dark pink tie. Finally, it has a little gold or silver metal edge, which makes it look happy and expensive.

Best man, just keep a low profile, and a gray shirt is ok, but personally it's a bit boring, so I suggest wearing white. Ties, depending on personal preference. If you want, you'd better choose a slightly lower-key color such as blue and purple, so don't steal the groom's thunder ~