there are many many types of batters here in italy. really it would almost be easier to define an italian-style batter by the types of batters they are not... what can be said is that if done well they should be crispy. and relatively thin unlike the beer batters of the better fish chip direction. The other obvious characteristic is that they are not spiced, at least traditionally. No herbs, no spices. otherwise there are batters that use egg (in some particular cases also cheese..), some that use milk, etc. etc..
my favourite, because it is simple, clean, and produces a crisp crust, is simply a mixture of sparkling water(cold, though ice cubes are unnecessary), flour, olive oil. briefly mixed to minimize gluten development.
all this has started to make me think of fried zucchini flowers... possibly coming up soon.