Hi,
It seems that G-2 version had both retractable and nonretractoble tail wheel.
According to Robert Pęczkowski's book about Bf109G version,Mushroom Model Magazine Special vol.I no 6101 the first changes to G-2 version were introduced in the autumn of 1942 when the new larger tyres were introduced.
The main landing gear had 660x160 tyres in place of the older 650x150 ones and the tail wheel with 350x135 instead of the 290x110 one.The rectractable tail wheel was abandoned in favour of fixed one in the same time.So before the modification was done, the G-2 version had been equipped with retractable tail wheel,I think