Palutena and Celestia would probably get along really well.
Twilight would be very by the book about everything, and AJ and Fluttershy would probably be quite competant. Rarity would probably do okay; she's good about details and working under stress, but given that she probably doesn't really like kids in general I don't know. Pinkie and RD...it really depends on whether they can buckle down and actually be somewhat serious about the situation.
That's the kind of question that you really wouldn't be able to answer without a lot of context, the largest unknown factor being who their partner is.
@ Mio: Well yeah Child Services will go for training on how to recognise awesome parents by observing one.
Tealove is best pony.
Pony Fanon Index
Oh hi everypony. What's going on?
Yeah, Andromeda is heading for you. You got over 9000 years until it collides.
This conversation reminds me of the Pokeparents meme.