One of my favorite "barbarian" armies of all time. I actually became interested in them from reading Robert E. Howard's "Conan" novels. Of course, his Picts are more like American Indians than Northern British Celts. However, it inspired me to read more about them and eventually, paint up an army.
This is one of my all time favorite paint jobs. I laboriously did tartan and checkered patterns on most the figs, as well as tattooes. A funny thing happened after I did the tattooes, though. Suddenly, it looked very weird for them to NOT have painted eyes. So, I was forced to go back and add a dash of black for the eyes -- the only time I have painted eyes on my 15mm figs.
These troops are rated different ways, depending on the rules used (and which version, in some cases!). However, they are the basic tribal infantry levy armed with spears. The old version of DBA rated them as warband, the newest as spears. Either way, they are a colorful sight lined up across a battlefield with their checkered or tartans cloaks or tunics, and blue woad tattooes.
The Picts used chariots until quite a later date than many armies. These were not the suicidal scythed chariots of lore that crashed into enemy ranks. Instead, they were used both as mobile platforms from which to launch javelins at the enemy, and also as a conveyance for warriors to act as mounted infantry.
The Picts also used light horsemen as scouts and skirmishers. Eventually, both the light horse and a heavier horseman replaced the chariots in Pictish armies. As with the charioteers, javelins were the main weapon. For an amy based in rough and hilly terrain of what is modern day Scotland, the Picts had a surprisingly large mounted force.
A large percentage of the Pictish army was composed of archers. It is thought they fought in a dispersed, skirmishing style, rather than as shoulder-to-shoulder, massed bowmen. This is logical as it would take advantage of the terrain of Scotland, or Pictland, I should say. And yes, the Picts DID use the crossbow. It is quite clearly pictured in the art they left behind (thought to be descended from the Late Roman crossbow rather than an early Medieval one).