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The Pokégear only has 3 features: Clock, Map, and Phone. The only thing of interest here is the Phone.
In the case of RSE, they have the television for the radio shows, the PokéNav for trainer calls, and a town map. There's really not much need for the clock since there is no day/night feature, although there is one on your room.
In FRLG, it is not needed because it is a remake of Gen 1. The Pokégear was not yet introduced in that generation.
In DPPt, again, they have the television, VS Seeker for rematches, a town map, and the Pokétch for the clock.
Now, in HGSS, we have it all together.
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Sorry, but I had to point this out.
There was a radio card. It was obtained by answerin 5 questions in the Radio Tower. It played music and there were a couple of other odd things that happened, like when you were at the Ruins of Alpha it played weird music, and at one point TR intercepted all signals.