I've used Doc's Pro Plugs for a while and they absolutely help. The only problem is that they do not stay in place well unless you either wear a hoodie or cap, or place the mask strap across the ears to hold them in place.
I have also been using a product called
Ear Shield which I like a lot. I've always had problems with water draining from my ears after submersion. But just a couple of squirts in ear ear before diving coats the ear canal and the water instantly drains when my head comes out of the water. At first I used both together but lately, I've been using the Ear Shield only since the plugs are a little bit of a nuisance at times, both for the reasons I stated above and also just keeping up with them.
But all that being said, neither will help your friend equalize. That is something he is going to have to figure out a way to do regardless of using either product. Even using the plugs and the spray I would have problems with my ears as I was using the Valsalva method of equalizing. I finally figured out how to equalize using my jaw and my ear problems have virtually disappeared. I found that moving my jaw forward is quite easy for me and I can equalize at will. You don't say what method of equalization your friend uses but there is a thread going now about the different methods.
Avoid the Valsalva Maneuver for Equalizing!