Wolves have enough intelligence to employ quite effective small unit tactics. Their Int score is lower than Elan's. I conclude that the combat tactics shown by various characters are not determined by a number on a character sheet.
On the opposite end: V is the "smartest" member of the order, but fought dumb until he realized he needed to work as a member of a team. Again, tactical choices are not being dictated by numbers on a sheet somewhere.
In the scene you reference, the Giant did not make an Int roll for Roy to think of that method. It is the sort of thing a player would think of, not based on a number on a sheet.
You can pick your terms, but tactics are being determined by personality and personal tenancies which do not use the D&D intelligence score.