I'm yet to see any of season 4, so if you meant specifically since Twilight became a princess then I wouldn't know. However, I think the show really started to focus more on them as a group in season 2, specifically following "Lesson Zero".

In seasons 2 and 3 I would still say that Twilight is the clear main character out of all of them (again, I can't comment on season 4 yet) but they have definitely started to focus more storylines around her friends as well.

That's one of the things I like about it, actually.

Yes. Although every show needs a primary protagonist, the writers seem to find the balance between Twilight and the rest of the Mane 6, who admittedly need some screen time. And I'm saying that even though Twi is one of my fave ponies. :)

^i agree ^^