Info Obtained from Switching and Beginning of Turn 1

[Oxypad]

I was browsing and found the following in Policy Review:
https://www.smogon.com/forums/threads/adv-switch-priority.3622189/

Since that thread seems dead and I cannot revive discussion there due to lack of privilege, I wanted to get some clarity on this subject, as it pertains to ADV.
Because:
(a) I have always wondered what sort of info about speed could be ascertained from when both players decide to switch their active Pokémon,
(b) There may be possible implications with mechanics when switching (I get the "Spikes sac" one, but the other one that comes to mind is Intimidate mirrors for the incoming mons trying to gain an advantage of lowering attack and not having their attack be lowered),
(c) and I'd like to understand if this is relateable to situations at the beginning of Turn 1 in cases like Tar vs. Tar or Zap vs. Zap or to see, for
example if, like, a lead Jynx is faster than a lead Salamence. (Or any lead situation really, since I would care about having an idea if my lead is faster or if the opponent's lead is faster.)

I know speed ties exist and lead to 50/50s (we all check battle logs to see who gets leftovers or is hit by sand first). And heck maybe I could watch enough replays to figure out the answers myself. But finding that thread lets me know that there may be purposeful coding going on and not randomness or something to overlook about switches when battling or watching a battle.

So apparently, the way Showdown! simulates ADV now is that switch order is not random, but actually based on speed.
"The faster Pokémon switches first" is a quote I saw posted. ("Switch Priority Clause Mod: Faster Pokémon switch first")

My questions are:

• In the context of when both players switch their actives, is it whoever's active Pokémon that is faster gets to execute their switch first? Would that be before mods (+/-, para effects) or with mods taken into account?
• In the context of the first turn when the lead pokes are brought out, is there any info we can determine about the relative speeds of the leads based upon the order of how they are revealed right at the beginning? How about the Tar vs. Tar lead where one whips up the sandstorm before the other one. Could something be made of that?

Can someone who was part of that thread shed light on this subject, or just explain it in a more systematic way. Is it just that simple that "The faster Pokémon switches first"? It has nothing to do with choosing to switch before or after the opponent in real time, or the speeds of the Pokémon coming into play, right? (Well maybe on Turn 1 which is what I'd really like to figure out.) Sounds like there is no one designated a "challenger" at the beginning of the match that would set up any sort of switch priority, or nothing at the beginning of the battle randomly chosen when it comes to switching.

I'm interested. Enlighten me. Thanks!

 

[byronthewellwell]

The faster pokemon switches out first (unless speed tie)

 

[Oxypad]

OK thanks. Just wanted someone to clarify that it is "Faster Pokémon switch first" and not "Faster Pokémon switch in first," or something weird like that. I will not overlook switch order anymore, regardless!

How about beginning of Turn 1?
Is it random who sends out their Pokémon first at beginning of Turn 1? Is there no info on lead vs. lead speed that can be determined then? Especially Tar vs. Tar leads?

 

[Astamatitos]

I've tested the turn one scenario with BKC about a year ago (prior to the official clause implementation).

At the time in challenge battles, it seemed that the switch priority of the lead was governed by who challenged. So for instance me and BKC would use a flygon and a faster zapdos and their order of switching in turn 1 was determined by who challenged the other player.

I haven't tested ladder yet to see whether a poke's speed or whether waiting time is the discerning factor.

I'd personally prefer that information to remain concealed (speed of the two leads).