Basic Units 8available to everyone):

Basic Infantry
Basic Fighter
Basic Bomber
Basic Destroyer
Basic Cruiser
Basic Battleship
Basic Battlecruiser
Basic Carrier
Basic Submarine
Basic Mot. Infantry

Germany:
Wehrmacht (basic infantry unit)
Waffen SS (some kind of "Special Forces")
Fallschirmjäger (elite airborne infantry)
PzKw I (light tank)
PzKw II (basic light tank)
PzKw III (basic medium tank)
PzKw IV (medium tank)
PzKw V (medium tank, later)
PzKw VI (heavy tank, later)
PzKw VI Tiger 2 (heavy tank, later)
Panzergrenadiere (mot. infantry)
Me-109 (basic fighter)
He-111 (basic bomber)
Ju-87 (unique german unit)
Fw-190 (improved fighter, appeared first in 1941, later)
Me-262 (jet fighter, later)
Ju-88 (medium bomber, ?)
88mm FlaK/PaK (unique german artillery)
sIG 33B/StuG (self-propelled artillery)
StuG 42 (self-propelled artillery, later)

Italy:
Basic Infantry
Militia (unique italian unit)
L6/40 (basic light tank)
M11/39 (basic medium tank)
M13/40 (basic medium tank)
Basic Fighter
Basic Bomber

Turkey:
Basic Infantry
Basic Fighter
Basic Bomber

Spain:
Basic Infantry
Republican Guard (unique spanish unit ;-)
T-26 (basic light tank)
BT-7 (basic fast tank)
T-28 (medium tank)
T-34/76 (basic medium tank)

USSR:
Red Army (basic infantry unit)
NKWD Troops/Red Guard (some kind of "Special Forces")
Siberian Troops (hardened troops, special winter warfare equipment)
T-26 (basic light tank)
BT-7 (basic fast tank)
T-28 (medium tank)
T-34/76/81 (basic medium tank)
KV-1/2 (heavy tank, later)
JS-1/2/3 (basic heavy tank, later)
SU-100 (tank destroyer)
Polikarpov I-16 (weak fighter)
Yeak-1/3/9 (basic fighter)
Pe-2 (bomber)
Il-2 Shturmovik (basic medium bomber)

France:
French Infantry (basic Infantry unit)
Renualt 35 (basic light tank)
Somua 35 (basic Medium tank)
Char 1 bis (basic heavy tank)
Dw 520 (basic fighter)
SL 45 (bomber)

Great Britain:
British Infantry (basic Infantry unit)
Commando (British Special Force)
Matilda MkII (infantry tank)
Crusader MkIII (basic cruiser tank)
Comet (cruiser tank, later)
Centurion MkI (heavy tank, later)
Spitfire MkII (basic fighter)
Swordfish (torpedo fighter)
Typhoon MkIb (Anti-tank Fighter)
Lanchaster (bomber)