As you probably know, some in-game events are unlocked if you go to a specific place while having a specific Pokémon on you or in the first party slot. What I want is a complete list of those events.
I'm mainly interested in events unlocking other Pokémon (such as the Sinjoh ruins event) and less in events unlocking items (such as the Gracidea event) or Formes (such as the Deoxys meteorites).
I know of the following:
- Arceus unlocks the Sinjoh ruins event in HG/SS. (any one, Movie and Azure Flute can unlock it once each) -> lets you pick Dialga, Palkia or Giratina.
- Celebi (Movie) unlocks Zorua event in B/W.
- Raikou, Entei or Suicune (Movie, shiny) unlocks Zoroark event in B/W.
- Regigigas (not sure where it's from, but it's Lv.100) unlocks Regi shrines in Platinum.
- Regice, Regirock and Registeel unlock that shrine where you can get Regigigas in D/P/Pt.
- Kyogre and Groudon (caught in HG or SS, respectively) unlock Rayquaza at the same location where the respective former Pokémon was found in HG/SS.
So, are there any more of these in Gen III+?