In Irish Gaelic,do the letters 'L','N' and 'R' each have three different pronunciations as they do in Scottish

All consonants in Irish have both a broad and a slender sound, depending on whether they are next to vowels which are broad (a, u, o) or slender (e, i). There isn't an aspirated slender as such in these rules, but there may be a lot of variation in the broad and slender of particular consonants such as "r", usually depending on dialect.