Did all the Beastman factions take part in Operation Archon

[Morningstar1337]

Okay so we know that a total of 12 faction took part in the literally Game-Changing Operation Archon. But as far as I know. The Scions, 3 Grand Companies, U Tribe and Sylphs were the factions I know participated. That is half the 12 factions. I also don't think the Holy See didn't partake in this because of their isolationism and dragon war but I could be wrong on that

I want to know if the other beastmen (Such as the Amall'ja in the Brotherhood of Ash) took part in the operation and what the other factions were.

[Enkidoh]

Technically from a gameplay standpoint because Operation Archon was part of the 'original' storyline from launch, it actually preceded the introduction of the 'friendly' beastmen factions, so only the sylphs took part (as they were already part of the storyline). Narrative wise, the sylphs took part in Operation Archon because they were already on friendly terms with Gridania and were also eager for revenge against the Garleans for Noraxia's death earlier in the game.

And you're right about Ishgard indeed not participating either - the earlier cutscene where the Alliance debates their options in regards to Gaius's ultimatum specifically states that Ishgard remained silent even with war virtually guaranteed. In fact, the whole Alliance were shown to be at the very least disappointed about Ishgard's stubborn refusal to assist the Alliance in their darkest hour, with Merlwyb particularly annoyed about it:

Kan-E-Senna: "Has there been no word from Ishgard?"
Raubahn: "None. The dragons have got their tongues."
Kan-E-Senna: "Silent to the last. I was unwise to hope for better."
Merlwyb: "What would stir the Archbishop to open his holy mouth, if not this?! And he claims the Fury for his god... 'Tis bad comedy!"
Nanamo Ul Namo: "The Holy See has made it's choice. We will proceed without it's cooperation."

So yes, Ishgard remained neutral during Operation Archon, it basically only involved the three main citystates forces (specifically, their Grand Companies), along with the 'free' sylphs, the Scions of the Seventh Dawn, numerous adventurer Free Companies, and smaller independent groups like Limsan pirate fleets and the Monetarist merchant faction in the Syndicate.

[LaurelinKementari]

I wonder if the peace we make with the beast tribe factions (Sylphs aside) will ever be reflected in the main scenario. Wish we'd gotten to see more of the Sylphs in operation Archon, too. They made such a big deal of the Sylphs being stricken and wanting revenge for the events after Titan's defeat, but when the moment finally got there, all we got was a "oh yeah, and the Sylphs are helping out, too". That part of the storyline felt a bit underdeveloped. Then again, I am a huge Sylph fan so perhaps I am biased.

[Kerberon]

I wonder if the peace we make with the beast tribe factions (Sylphs aside) will ever be reflected in the main scenario. Wish we'd gotten to see more of the Sylphs in operation Archon, too. They made such a big deal of the Sylphs being stricken and wanting revenge for the events after Titan's defeat, but when the moment finally got there, all we got was a "oh yeah, and the Sylphs are helping out, too". That part of the storyline felt a bit underdeveloped. Then again, I am a huge Sylph fan so perhaps I am biased.

Well you'll probably get more Sylph content with Ramuh.

[Catapult]

Lets see of we can list the possible factions off...

The Scions of the 7th Dawn
The Adventurers' Guild (incl Revenant's Toll)
The U tribe
The Immortal flames
The Brass Blades
The Sultansworn
The Stone Torches
The Maelstrom
The Bloody Executioners
The Yellowjackets
The Kraken's Arms
The Sanguine Sirens
The Order of the Twin Adder
Little Soalce
The Wood Wailers
The God's Quiver
The Coeurlclaw
The Redbellies

I count 18 possible factions, not including the beast tribes bar the Sylphs, not all of which may have been engaged independantly or as part of a larger faction.
We mustn't understate the internal conflicts within the city-states and the significance of bringing them together for this. I think that is the message Alphinaud is trying to impart.