Do you know what sort of military tactical doctrine was typical in Scotland in the late middle ages? I know pike formations were common, but what would be used in support? Also, were said pike formations vulnerable to missile fire (like, say, Welsh/English longbowmen)?

The Medieval Scots relied on the schiltron, a formation of pikes that was originally circular and then transformed into a rectangle thanks to Robert the Bruce. While effective at holding off English cavalry and dismounted men-at-arms, it was really vulnerable to the English and Welsh longbowmen due to the tight-packed, static infantry being a really good target for archers, hence the Scots’ defeat at the Battle of Falkirk.

The rectangular schiltrons that the Bruce introduced at Glen Trool and then exploited to devastating effect at Bannockburn were far more mobile and better-trained, allowing them to be used both defensively and offensively. It also helped that the Bruce kept his cavalry close in hand to protect his schiltrons by driving off any offensive use of longbowmen, whereas often before the Scottish cavalry had fought independently against the English cavalry and often been driven off the field, leaving the schiltrons exposed (as happened at Falkirk).