I believe your friend is making one major mistake in "giving the dogs equal time." Gunner will adjust to the pup being around better if he doesn't think his position is threatened. He needs to be affirmed as the alpha dog over the two of them. Basically your friend is going to have to give Gunner the first attention, first pet, first to eat, first to go out, first in everything.

Is Gunner neutered or in tact? As Memphis gets older (I assume when you say a new puppy, we are talking under 16 weeks old), and begins to come into her maturity, she may challenge Gunner for the alpha spot but that is down the road a bit. Right now you need to get Gunner comfortable with the situation.

Don't expect them to ever be best buds. Gunner will probably learn to "tolerate" the pup and the pup will look to Gunner as a role model figure! They will need to work this out for themselves.

In short, about the only thing you can tell your friend to do now is to treat Gunner as alpha so he doesn't feel threatened that the pup is taking over. As for the toys, let them work that out too! But if you choose to give the pup a particular toy, then Gunner needs to accept that since the human being is the ultimate alpha over both dogs!