1983:

Rainbow Ponies

Ahh. Rainbow Ponies. The original "gimmick" set.

Unlike other little ponies, the Rainbow Ponies had a special feature - each of them had a mane and tail in four colours (dark pink, yellow, green, blue), ostensibly to mark out the colour of the pony rainbow. Each pony also had a glittery symbol - this set featured the first earth ponies to have glittered symbols.

Because they were gimmicky, probably, and because they had such pretty hair, the Rainbow Ponies from this year are pretty commonly found second hand. All of them were sold globally, and appear to have had the same accessories the world over. In the UK, at least, according to the 1985 Argos catalogue, they retailed for £2.85.

STARSHINE, advertised in the 1985 UK ARGOS CATALOGUE
(Thanks to Garej for this scan)

Myself, I have a soft spot for the Rainbow set, since my first ever little pony was Windy :)

The Rainbow idea would return again in a year, featuring more bold rainbow colours and brighter body tones.