Chatterbox
CHATTERBOX
(pink with purple and dark pink mane and tail, two ponies talking in a heart)
Sweet Talking Ponies
The role of the Sweet Talking Ponies in the UK is odd - Chatterbox (the pink one) appeared in several comic stories as an irritating and inqusitive character, whilst Talk-A-Lot (the purple one) made only one comic appearance. For a long time it was almost as if Talk-A-Lot did not exist, since on the insert for 1991 only Chatterbox is shown, but when they were actually sold both ponies were issued in UK packaging on British shelves. I know they came with long-handled combs, and spoke three phrases 'I'm Pretty', 'I love you', and 'Comb my hair'. In Spain and, one assumes, in South America the ponies were called Mimoso (pink) and Charlatan (purple) and their phrases were 'Peiname (comb me), 'Dame un besito' (Give me a little kiss) and 'Vamos a jugar' (Lets go play!). The German version only spoke two phrases - 'Ich Hab Dich Lieb' (I love you') and 'Kommst Du Mein Haar?" (Will you comb my hair?).  I believe their names are Goldstimmchen (Golden Little Voice - Chatterbox) and Goldkehlchen (Little Golden Throat - Talk a Lot). Thanks to Sarahkittywinks for this information :)
I don't know if there are French Sweet Talking Ponies. I'd really love to get one if there are :D.
The ponies themselves do not vary in colour or style between countries, only their language boxes change.
There is an ENORMOUS amount of confusion over the names of these two ponies. When it was first discovered internationally that in the UK these ponies had names there was an amount of excitement generated but the names were totally confused when they were broadcast to the net as a whole. So, in order to settle once and for all *which* is Chatterbox, and *which* is Talk-A-Lot, I've included a picture of my Mint in Box Talk-a-lot (Click image to see full size).
In the US, these ponies were sold on card, not in box, for I have the pink one MOC.
Anyone who has any further doubt about the names of the Sweet Talking Ponies can put their minds at rest by checking out the information on the side of Talk-A-Lot's box (Which I think proves it once and for all). 
Talk-A-Lot
TALK-A-LOT
(purple with dark pink and dark purple mane and tail, two ponies talking on the phone)
Talk-A-Lot MIB
TALK-A-LOT MINT IN UK BOX