Hmmm...
Pearl: 300+ (Can't remember the exact number.) Can't remember exactly what I was doing for all those hours. O__o; Probably just running around and doing random things. That was before I got into competitive stuff and chaining.
Platinum: 525 and some minutes. At least a quarter, maybe more, of that is chaining. Another quarter or more is battles. The rest is completing the game, getting 999 of every kind of Pokeball you can buy, along with 999 of every repel, raising things, getting a 497'd Pokedex, farming items underground, filling out my villa... Etc. I'd be very, very sad if this save file disappeared on me.
Heart Gold: 64 and some minutes. Still working on completing Kanto. :3 After I finish the game, time will likely continue to grow a lot, as the new IV passing system seems very appealing to me.
- Tyros