I think this campaign could be cool if it focused more on only Italy as the main Axis, against mainly America and Britain.
For starter rifles, Axis would get the Carcano M41 versus the Allies 1903 Springfield.
At level 1:
Rifleman Squad, Carcano Mod. 38(7.35mm) (Axis), Ross Mk. III Rifle(Allies)
Assaulter Squad, Beretta M1918(Axis), STEN Mk. I(Allies)
Sniper Squad, Carcano Mod. 38 Sniper(Axis), Springfield 1903A1(Allies)
At Level 2, we get Tanker I Squad, with:
L6/40 light tank for Axis, against M8 “Greyhound” for Allies.
Level 3 gives Engineer Squads, and the rifles:
Carcano M1891(Axis), and M1917 Enfield(Allies).
Level 4:
Beretta M38(20 Rounds) for Axis, Lanchester for Allies.
Level 5:
AT Gunner Squad, Fucile Controcarro 1935(Axis), Boys AT Rifle(Allies).
Level 6:
M14/41(Axis), and M3 Light Tank(Allies).
Level 7:
Radio Operator Squad, Gewehr 98/40(7.92mm rifle based on Carcano action) for Axis and Lee-Enfield No. 4 Mk. I for Allies.
Level 8:
Machine Gunner Squad, Breda Mod. 30 for Axis, Bren Mk. II for Allies(don’t worry, Italians have better LMG up their sleeve)
Level 9:
Armaguerra Mod. 39(Axis), and M1 Carbine(Allies)
Level 10:
Fighter Pilot I Squad, with CR.42 “Falco” for Axis and Hurricane Mk. II C for Allies.
Level 11:
Beretta M38/42 for Axis, and Browning Auto-5 for Allies.
Level 12:
Tanker II Squad, with:
SOMUA S35 for Axis, and M8 Scott for Allies.
Level 13:
Madsen for Axis and Browning M1918A1 for Allies(Madsen is better than most think)
Level 14:
Attacker Pilot I Squad, Breda Ba.65 for Axis and Bristol Blenheim for Allies.
Level 15:
Flametrooper Squad, Flammen 35 Axis, M1 Flamethrowe Allies.
Level 16:
Mortar squad, dont care much for them
Level 17:
M15/42(basically M14 but with longer 47mm gun), and M3 Lee(w/75mm M3 gun) for Allies.
Level 18:
Assaulter II Squad, ZK-383 Axis, M1A1 Thompson Allies.
Level 19:
Fighter Pilot II Squad, Re. 2005 Axis, Spitfire Mk. Vb for Allies.
Level 20: Engineer II Squad, Armaguerra Mod. 39(7.35mm) Axis, M1A1 Carbine(w/ Bayonet Lug) for Allies.
Level 21:
Sniper II Squad, Sniper Carcano M1891 Axis, M1903A4 Allies.
Level 22:
Tanker III Squad with Semovente 90/53(Glass cannon that can probably OHKO most Allied armor INCLUDING SHERMAN AND LEE), versus M4A1 Sherman for Allies.
Level 23:
Machine Gunner II Squad, Madsen(40 Rounds) for Axis, BAR M1918A2 for Allies.
Level 24:
Beretta M38(40 Rounds) Axis, versus M1 Thompson(Allies)
NEW GOLD ORDER WEAPONS:
Vetterli Vitali M1870/87: A 10.54mm rifle, with a 4-shot mag. It would have a whopping 18.5 damage out to 10 meters, but this would rapidly fall off past 100m. due to a low velocity of 430m/s, making it a medium range skill/meme cannon similar to a Berdan or Gewehr 1888.
United Defense M42. American 9mm SMG intended for use with resistance forces, had a moderate fire rate, two mags were welded together for quick reloads.
Post more level suggestions/ideas for changes in comments!