Acid rain glitch -- why does it occur?

[Blaziken257]

I'm going to assume that most people know about the Acid rain glitch. If not, here's a quick explanation: In Platinum, HeartGold, or SoulSilver, if you use Pursuit on a Pokémon that attempts to switch and faints while there is some weather effect (like Sunny Day) or a field effect (like Trick Room), the game goes nuts, multiple effects occur at once, and Pokémon are hurt by their own abilities. A more detailed explanation is here.

I'm posting a topic about this because I'm curious to why the glitch occurs. If people can figure out why MissingNo. works the way it does, and what determines the species/level in the Mew glitch in R/B/Y, surely someone can figure out what causes this glitch to occur. In other words: Why does Pursuit, a move that has nothing to do with weather, cause multiple weather/field effects to occur if it knocks out a switching Pokémon? Also, how does it cause Pokémon to be hurt by their own abilities? This probably has something to do with Solar Power, which damages Pokémon with this ability when it's sunny. But it's strange that this glitch extends to any ability, and apparently it occurs even when the sun is not out. Finally, how do multiple weather effects even occur at once? I didn't even know that was possible. I would think that the game would be programmed to only allow one weather effect to occur at a time.

It's strange that Pursuit causes this. Pursuit and the weather shouldn't be related, period. But with this glitch, it is.

Finally, it's strange how the glitch was actually introduced in Platinum. Usually glitches in a generation start in the first versions then get fixed in later ones, but in this case it's the exact opposite. Some programmer obviously messed up here...

[Torchickens]

It only occurs when Pursuit is the host, and will happen if the user of Pursuit was on Platinum/HG/SS but the opponent that fainted was on Diamond/Pearl.

I find it interesting that Pursuit is priority +7 when switching out. Maybe when a Pokémon faints due to Pursuit, the game was reverting the priority of its 'field moves' back to +0 minimum because there are no Pokémon on the opponent's field? Perhaps if a weather effect was already in effect then the game would cycle through all other weather effects before it in priority like what the glitch does.

No idea about Pokémon getting hurt by their own abilities.

[Blaziken257]

That priority explanation makes sense, although I was hoping that someone here had some technical understanding of how it worked (like looking at the game's programming and such). Oh well.