Hello Jonathan!

Almost every battalion could skirmish. The SK system simply rates them according to how well they generally did it. 0SK covers those who were generally not very good at it. 1SK represents those who generally had light companies attached, but also includes those who could also use other companies. 2SK covers all light infantry battalions unless they were known to be deficent in skirmish training. Some people extend the 2SK rating to other units that although intended for other purposes they could also skirmish very well (Grenadiers, Guards etc.). Just be careful to who you give an SK2 rating to as it's a strong modifier.

So no everything should not be rated as SK2.

It's not unusal to find situations where everybody is skirmishing and doing a good job at it. So in a given scenario you could actually rate everybody as SK2 if you felt it would give you a better representation.  You could also go the other way and rate everybody SK1. It's all up to you.

Does this make it clearer? If not let me know and I'll try and give it another go.

Best regards,

Glenn