What are those men doing at the beach wedding. Why they waving?

Whatever they're doing it's really weird lol! Actually it's an example of lazy animation. They've literally taken the same guy and repeated him 5 times with no change. I find quite a few of these new decorations you get from completing the memoirs poorly done.

Not sure exactly which scene you mean, but I suspect they are Nicky, who is June's ex-husband, and his significant other, Joseph.

My thoughts were that the men all know that the bride is marrying the wrong man and are slapping their faces in disbelief, folding their arms grumpily and then pointing to the guy waiting on the beach. I'm probably way off, but it makes for a more interesting story that way.