RE: The HG/SS Question and Answers thread
In addition to that! The Bug-Catching contest is every Tuesday, Thursday and Saturday. There are seven Day Siblings that you can talk to for their items. Every Monday and Wednesday you can battle your Rival at the Indigo Plateau (after you beat him at Mt. Moon). Every Monday night, at or around midnight, you can watch the Clefairies dance at Mt. Moon clearing to get a free Moonstone. Also, based on beating Red (I think), you can challenge all 16 Gym Leaders again by catching them away from their gyms at certain times and registering their phone number, then calling them at a certain time for a rematch.
Also, a few more Pokemon: If you have Arceus, you can generate either Palkia, Dialga or Giratina (which are holding their respectful hold items) at Lv 1 someplace. Also, if you bring the Pikachu-colored Pichu from Gamestop to Ilex Forest with a space in your party, you'll befriend Spiky Eared Pichu.
Also, through some sort of sidequests, you can catch either Kyogre or Groudon (depending on version) in game, as well as Rayquaza. I'm unsure of the exact requirements on how to meet them, but I think 16 badges is one of them.
Also, there's a super-secret Celebi event programmed into the game as well that gives a little backstory into Team Rocket and your rival. We haven't gotten a Celebi in a very long time though, so unless they give us a download event, this is the hardest event to really do.
Uuuuuum, that's all off the top of my head, last I checked.
Oh! And if you get 5 Shiny Leafs stuck on one of your Pokemon you can get a star for your Trainer Card as well as something cool for that Pokemon. Though it's kinda a small event...
Yep I think I got most of the events.