I can only go back to the 1950's so I can't comment on what was worn before that although I suspect it was much the same as dress styles only changed slightly during the 20th century. A catalogue printed in the 1950's describes formal dress as a dress doublet of black or green cloth or velvet, single breasted with tassets(Inverness flaps) and gauntlet cuffs. It can be worn unbuttoned with a waistcoat but the more modern style(1950's) was buttoned up without a waistcoat. Accessories were tartan hose, full dicing and overcheck throughout, plaid, either long shoulder plaid or shorter belted plaid. A sporan is usually white goat hair or sealskin but may also be in animal fur or skin with silver or gilt mountings. Leather sporans are for day wear only. Add to this a basket hilted sword, cross-belt with frog for the sword, a dirk, waist belt, sgiandubh, kilt pin, jabot and cuffs of old style lace, patent leather brogues with engraved silver buckles and either a Glengarry or the older Balmoral style bonnet with silver crest or badge and feather or feathers "for those entitled to wear them". It goes on to add "Highland pistols and Powder Horn may be worn in full Levee Dress".
I suspect that this form of dress probably goes back perhaps as far as Victorian times.
An alternative form of dress is given as wearing "The coatee known as the 'Prince Charlie Coatee' and sometimes as the 'Atholl Coatee'" for all evening functions except Court Levees when the Dress Doublet is obligatory. The Coatee is described as buttoned up without a waistcoat but the more modern style unbuttoned with a waistcoat so this indicates what we wear nowadays probably became fashionable in the 1950's. It also stated that the facings (lapels) of the coatee should not be of silk but the same material as the rest of the jacket and I believe this is still the case. Epaulettes in those days were flat fabric and not the braided ones seen today. Buttons on all jackets were either round or diamond silver, plain or with a crest or cut steel and also in black in different designs.
A jabot is worn with the buttoned up coatee and a wing collar and bow tie if unbuttoned with a waistcoat. All the accessories described earlier can be worn although dirk and belt are optional.
Alternative jackets for formal evening wear were the double-breasted dress doublet (called a Montrose nowadays), A Montrose doublet (now called a Kenmore), single breasted with tassets (Inverness flaps), the Argyll doublet which was similar to the double breasted doublet although single breasted and all were worn with a jabot and cuffs. There was also a dress kilt jacket and waistcoat very similar to a tweed Argyll jacket but in velvet with silver buttons. In my lifetime fashion has changed from mostly wearing the double breasted doublet to almost universally wearing the Prince Charlie. Also white socks were unknown but are now almost universal, probably thanks to the dress-hire companies. If self coloured socks were worn they were a beige colour or something to tone in with the kilt.
Ghillie brogues are not mentioned at all at this time so must have been a later introduction. For formal wear patent leather brogues with silver buckles which fastened either with a strap or laces or a slip-on style not unlike today's "penny loafers" but in black patent leather with silver buckles were the universal footwear. For daywear strong black leather brogues were worn.
For daywear the jacket was either plain with plain sleeves without celtic gauntlet cuffs and pockets or the Argyll with gauntlet cuffs, shoulder straps and pointed flaps and buttons to the lower pockets. Both had staghorn buttons. The sporan is of plain leather or pigskin or plain fur (i.e. no silver or gilt mounts)