My G2's always changed personalities and such, so they were never the same ponies, but if I needed a boy, Sun Sparkle would be one. Didn't like her much so she wasn't much played with... Magic Motion Ivy would sometimes be one too. I didn't often have ponies playing boys because my ponies were always going on adventures and I didn't get the need for boys. I seldom played they were in families (the babies were always oddly independent and parentless
).
But then, it's hard to tell which G2's are boys unless you read their cards, because of their lack of... differences from the females :-P