3rd Gen Pokemon Center Men

[Palamon]

In the Mauville City Pokemon Center, there will be a man there that depends on your Trainer ID and save file. There are five different ones. Their names are Giddy, Hipster, Bard, The Trader, and The Storyteller.

According to Bulbapedia, this is what determines which one will appear in your game:

In Ruby, Sapphire, and Emerald, the final digit of the player's Trainer ID number determines which of the five men will initially appear in the Mauville City Pokémon Center. The following list details which number corresponds with which man.
If the Trainer's ID ends in 0 or 1, the Bard will appear.
If the Trainer's ID ends in 2 or 3, the Hipster will appear.
If the Trainer's ID ends in 4 or 5, the Trader will appear.
If the Trainer's ID ends in 6 or 7, the Storyteller will appear.
If the Trainer's ID ends in 8 or 9, Giddy will appear.
If two or more players of Pokémon Ruby, Sapphire or Emerald mix records with each other, the men that were in each players' games will be transferred over. The player is allowed one interaction with the man that initially appears in their game, as well as one interaction with each man they receive from another player through record mixing.

If you get Giddy, he will ask you a series of yes or no questions. Hipster will add a phrase to your easy chat system, but only once if you never mix records with anyone. The Bard will sing six words within said easy chat system. The Storyteller will tell you up to four stories until you mix records for more. I believe most of the stories are just stuff that have to do with the player, though. Finally, the trader will trade Secret Base decorations with you.

In the remakes I think you can meet all of the Pokemon Center Men, and they... fuse together to become Mr. Bonding. It's really freaky and weird.

There's also Pokemon Center ladies as well. They only appear in Pokemon Emerald. There's only three, however, and they were never carried over to ORAS. These women are the Contest Lady who will ask you for one Pokeblock. She will either have a Skitty that needs a Dry Pokeblock, a Poochyena that needs a Sweet Pokeblock, a Pikachu that needs a Sour Pokeblock, a Kecleon that needs a Bitter Pokeblock, or a Zigzagoon that needs a Dry Pokeblock. There's the Favor Lady, who will ask for a specific type of item once a day, and she will give you a vitamin in return. Finally, there's the quiz lady that will only appear if you mix records, so you'll probably never see her. She will ask you questions, however, and will give you prizes such as TM Hyper Beam and Big Pearls.

Which Pokemon Center Man was in your game? I think I had the Trader and the Storyteller, but I don't remember any more. It's a really useless thing that can't have anything done with these days since I don't have a GBA.

As for Pokemon Center Lady, which one was in your game in Emerald? I also had the Contest Lady, but never gave her a Pokeblock, so LOL, sucks to be her!

 

[Amore]

In terms of the guys, I think I've noticed all of them. I got really into Secret Bases though, so definitely prefer getting the Trader. For the women, the only one I've ever noticed it the Pokéblok lady.
As I never had - and never will have - anyone to mix records with its slightly frustrating, but at least with this mechanic you do still get some of the experience, unlike how I can't do any trade evolutions in Gen III.