Ok, I know I'm new here, so what I say may not carry as much weight, but there are few things I want to say.
There was and never has been a tank designated Hellcat. That was the Navy carrier-based fighter-bomber in action 1943 on.
tcwonder3
M18 Hellcat Tank Destroyer, USA I know this is nitpicking, unless you dont count the tank destroyer as a real tank.
The soviet airplanes are a nice idea because not the "battle of britain" was the biggest airbattle ever but the "battle of Kursk"summer 1943.
Lurchfang
The battle of Krusk was the biggest tank battle in history.
Ok, now to the tanks and the strengths that should be included :
Germany:
Panzer I or II, either or very weak tanks, the Pz. I being armed with dual machine guns and nothing more, and the II having only a 20mm cannon. They were produced in large numbers and used until around 1942.
Panzer III
Two different versions of this tank were made, the initial one with the low velocity gun (50mm) saw action until it was upgraded to the newer Ausf J with the longer-barreled gun to try to counter the T-34 and KV-1 tanks the Germans were encountering on the Ostfront. (this increased the velocity at which the projectile moves, increasing the AP ability. Longer barrels = better basicaly)
Panzer IV
This tank should be included no matter what, as it was the most influentual German tank alongside the Panther, it was also produced in large numbers (by German standards

) up until the end of the war. The first vcersion was devised by Manstein in his view that he would need a tank (Pz III) to serve in the Anti-Tank role, while a another tank to hit personal targets. This is where the Pz IV was introduced, with a short barreled 75mm gun. It was later upgraded to Ausf G with the longer barreled 75mm gun that could better counter the Russian tanks. Another version, Ausf L added better protection for the tracks, and further extended the gun barrel length (from L/40 to L/48).
Panther
Were devised to counter the Russian tanks and "burrowed"many of the design traits of the T-34. The first Panthers were employed at Kursk, where they suffered from mechanical problems (which were never fully solved throughout the war). The Panther employed a excellent 75mm gun that was almost (or equal) to the Tiger's 88mm gun. The sloped armor provided awesome protection which the Sherman's low velocity 75mm guns had a lot of trouble penetrating.
Tiger:
Produced in very small numbers (only about 1400) they were slow, heavy and suffered from mechanical problems. They also employed the same flak88mm gun used on the German 88s, and had excellent armor. Not much else to say.
It should also be noted that Stugs, Hetzers and their variations of SPG's were produced in great numbers and contributed greatly to the German fighting effort.
Soviets
BT-5 or 7
Lightly armed and armored Russian tanks using the Christie suspension system.Very fast, but not very powerful tanks.
T-34/76
Some say the best tank in the war, except for its lack of a better gun, it certainly would fit the bill for an almost perfect tank. Employing the Christie suspension system(that the USA refused to buy

) and sloped armor, as well as wide tracks which gave it better cross country ability, the Germans had a tough time fighting these things, which lead to the Panther etc. etc.
KV-1
Used the same gun as the T-34, but with even better armor.
KV-1s
An improved KV-1 not worth mentioing
KV-2
A modified KV-1 that had a huge box like turret, and emplyed a huge howitzer like cannon. Very powerful, but cumbersome,and it was too easy to hit.
KV-85
A KV-1 tank with a long barreled 85mm gun with improved armor.
T34/85
Improved armor, and a long barreled 85mm gun to boot.
IS-2 (Iosef Staln)
Had 120mm gun and a ton of armor, played a major role in clearing the suburbs of Berlin and the German countryside of Bunkers, Tigers etc.
NOTE: Iosef is the Russian word for Joseph.
IS-3
Saw too little action in WW2 too be included.
The Russians also produced a wide range of SU guns (SU-76,SU85,SU100,SU122,SU152) that also served much the samerole as the German SPGs.
America
M3 Stuart
Crappy light tank with 37mm "door-knocker".
M5 Stuart
Much improved stuart.
M3 Grant
A stop-gap solution. Employed a 37mm gun in the turret and a 75mm gun in the hull with limited traverse. Had decent armor, but as one American tank commander put it "it looks like a damn cathedral coming down the road"
M4 Sherman
Improved armor, good reliability and more imprtantly, cheap to manufacture, these things were decent tanks, but unfortunately, only the British managed to get full use out of it by putting a 17pdr (76.2mm) long barreled gun on it. Otherwise the Sherman crews had to deal with either a 75mm or 76mm gun, that had poor velocity and couldnt penetrade Panther or Tiger armor unless at close range.
M10 Wolverine TANK DESTROYER
Since the US government didnt think tanks job was to kill other tanks, they regulated this task to tank destroyers The M10 featured an open topped turret with a long barrelted 76mm gun.
M18 Hellcat TANK DESTROYER
Virtually no armor, but extremely fast. Same 76mm gun.
M36 Slugger TANK DESTROYER
Good armor protection with a 90 or 76 mm long barreled gun (sry, I cant remember).
M26 Pershing
Saw very limited action, so I wouldnt include them. Similiar to the Panther, had a 90mm long barreled gun and good armor protection.
Britain
Matillda
Heavily armored, very slow "Infantry" tank witha pny 2 pdr gun that couldnt be upgraded because of the small turret.
Crusader
Used the Christie suspension system. Fast tank, but poor armor, a porr 2 pdr gun (that was later upgraded to a 6pdr)
and frequent breakdowns.
Valentine
Another "Infantry" tank, similiar to the Matilida, except it had less armor for speed.
Cromwell
Carried a 6pdr gun with decent armor protection and speed.
Churchill and its many different versions
A huge, slow tank with good armor, and a 6pdr howitzer that lack HE shells which vastly weaked its anti-personall effectiveness.
The brits made other tanks, but they never made enough of them imho to have them listed or included.
Other
French S-35
Considred the best tank in the world at the time,had a 47mm gun, good armor for its time and decent speed. Only about 600 were made and they were squandored because of poor tactics.
Char B-1bis
Huge tank that caused teh Germans isolated problems, but were never massed to really do anything big. Had a 47mm gun in the turret, and a 75mm in the hull. Massively armored for its time.
Czech Pz (38)t and (35)t
Were made by the Skoda manufacturing plants, were captured and used by the germans extensively. The 38t being a fast,but lightly armored tank that had a decent gun.
Vickers 6-ton tank (many countries)
Sold by England to many countries, primitive tanks outdated by WWII.
Italian M13/40
Emplyed a 47mm gun and a god-awful design (sorry, but its true), with terrible armor. Dubbed Iron coffins.
Italian Semnovette (might be spelled wrong)
SPG based on the M13 chassis, very succesful, mounted a 75mm gun with layerd armor that provided good armor protection against allied tanks.
Well, I think that should cover your tank needs
