Boy do I have some things to say about Siberians!!

I did a lot of research into the Siberians for CEAW, and generally speaking the arrival of a big bunch of veteran troops at Moscow in late 1941 is a myth.
About 100,000 Siberian infantry arrived from August-December in 12 or so divisions, but they arrived 1 division at a time, and were spread out around several armies - 2 divisions went to the 7th Army covering the Svir river border with Finland.
The Siberians were not veterans any more than other conscripts in the army were. the USSR had a conscript army, and the Kalkhin gol had been almost 2 exactly years previously - so all the conscripts from that conflict had left the ranks! There is some mention in one source of an army (24th army?) assembling in the Ukraine I think that mentions some concentration of "Siberian" veterans.
the number of "Siberians" who actually fought the Japanese was quite small - IRC 2 infantry divisions, a couple of tank and machine-gun brigades is all. there were more Soviet veterans from the Finland war!
I did once post a list of the rifle divisions sent from east of the Urals, but I can't find it anywhere so I'll use this one from slitherine's CEAW forum to illustrate the point:
Siberian units sent west in 1941:
Central Asian MD
2 of the 4 Rifle Divs moved - 194 (Mtn) Sep 41 and 238 Oct 41
Trans Baikal MD
3 of the 4 Rifle Divs moved - 65 Oct 41 93 Nov 41 114 Oct 41
Far Eastern MD
5 of the 16 Rifle Divs moved (21,26,32,92,70) although 92 did not go to Moscow but Leningrad.
101st Mtn (possibly 101st Motorised?) which was also sent west in Oct 41.
69th Motorised might have been an ordinary Rifle Div but whatever it was it was sent west and destroyed in Oct 41.
Info from "The Red Army Order of Battle in the Great Patrotic War" - Pairier and Conner.
note that many of the "siberians" units were not from the Far Eastern military district (which is the one facing the Japanese), and some of them were destroyed as units well before December 1941.
The Russian troops that rolled up the Germans in December 1941 were mostly new troops that had been held in reserve and given some training and decent equipment, and hte Germans had no idea that they existed. So the Germans thought the Russians must have called up units from reserve somewhere...and Siberia was the obvious place, so they all got called "Siberians".
Now IMO this is one of the things that AT can do quite well - you can riase a few new armies and hold them behind Moscow for a bit to allow them to train up - the "frontline" armies can be fed just enough replacements to keep them alive, while these new armies are getting better turn by turn.
And that's pretty much what the Soviets did.
So if you want to simulate Siberians the division numbers are above & you can give them one-off reinforcements of 1 division for each of those at the appropriate time. In addition the Soviets transfered 300 tanks and 1000 a/c - all of them obsolete types (there were no T34's in Siberia for example), so a few units of low tech a/c and armour could be added too.