>>43968077Time based events won't work, most of them are irrelevant in regards to Pokedex completion, however there are two time-based events that are important:
1) Shoal Cave will be locked into high tide or low tide, low tide is required to catch Snorunt, high tide doesn't have any exclusive Pokemon (it does let you make Shell Bells, although you need low tide to collect Shoal Salt anyway)
2) The day/night cycle doesn't work, so you're locked into either getting an Espeon or Umbreon when you evolve Eevee
The latter can be solved by just setting the clock to low tide. The former requires you to play through RSE at least twice with the clock set at different times.
As a side note, it's much easier to complete the gen 3 Pokedex if you have the Gamecube games. Completing the Pokedex using just the GBA games requires all 5 games and you need to play through Emerald and complete the Hoenn Pokedex 3 times to get all the Johto starters. If you have Colosseum and XD, you only need Emerald and Leaf Green (Leaf Green is required instead of Fire Red because Slowpoke is exclusive to that game). You will also need to play both Emerald and Leaf Green twice to get all the fossils and Latias/Latios.