There is some doubt that the Greek army had any tanks at all when Italy invaded.  It is generally accepted that they had purchased a few single specimans for testing purposes over the years preceeding the War.  It is also generally accepted that the few orders they did make for tanks with france, Great Britain and The Netherlands were all cancelled for one reason or another -- no tanks other than test models ever reached the Greeks before Italy invaded.  Even the exact models they tested is open to question, and whether or not they were able to be used even if they still had them.*
*
Keep this in mind when considering any tank purchases. For game purposes, consider there is available (not counting captured tanks, or British tanks): 1 FT-17, 1 FT-18, 1 Renault AMR-33, 1 Char NC1(f), 1 Char NC2, 1 Char-D1, and 2 Vickers Mk E (1 "a" variant and 1 "b" variant) -- 8 tanks total.  As mentioned above, even the specific models available are controversial.  It is possible that the Greeks had a Vickers MkVIb instead of the Renault AMR-33, and any one of several models of tanks instead of the Char-D1.  The other models are generally accepted as definite test purchases, though whether they were operational in 1940 is another matter.