This represents the survivors of Gil-Galad's Kingdom of Lindon after the Last Alliance until the destruction of Angmar, after which Lindon did not go to war again and many of its inhabitants crossed the seas. As uch it is the last Elven army in Middle Earth to include significant numbers of Noldor and Sindar. Cirdan or Elrond commanded and a significant cavalry component helped out flank the forces of the Witch-King in the decisive Battle of Fornost after the fall of Arthedain, in which a large force from Gondor and the remnants of Arthedain also fought. Dwarven allies are not mentioned but the possibility exists that the remain of the Houses of Belegost or Nogrod fought with Lindon.
Imladris troops can be part of any other elven command and vise versa.
It is unclear whether Elrond or Cirdan commanded, I would recommend for scenarios or campaigns the elves could be given two CinC's. If poss you could pass this back to the chap who wrote it. It's only a real small point but an important one. He seems to have neglected to consider Glorfindel, who was the defender of Rivendell and the one who led the elven forces against Angmar in 1975 when Fornost Erain finally fell. Glorfindel was certainly the foremost elven military commander left in Middle Earth after the death of Gil-Galad.