with my

[Unregistered]

Are these correct? Do I need to insert "my"? When do I not need an article after "with"

I play with my teammates
I play with teammates


I ate with friends
I ate with my friends

 

[Wuisi]

I think it depends on the group you're referring to: my friends, my mates implies a particular (well-defined) group; friends, mates (non-defined), just friends you happen to come across or people in general you refer to as friends -anybody would do-.