The mercenaries I am referring to are those employed by the Swedes. They are named in the documents I attached previously in this thread. In 1611-1613 these and several more included:
InfantryBodyguard(infantry) company of Jacob de la Gardie led by Daniel Hepburne with German soldiers
Jacob de la Gardie's Regiment of 7 German companies (Grey dress)
Infantry Regiment led by Samuel Cobron, 9 companies of English and Scottish but also one German company and one from Switzerland. (Blue and grey dress)
Infantry Regiment led by Reinhold Taube, 3 German companies, 2 Scottish, 1 Polish
Infantry Regiment led by Johan Mönnichhofen, 5 Dutch companies (Blue and grey dress)
CavalryOne Scottish company under Patrick Ruthwen
One Scottish company under John Wacop
One Scottish company under John Sutherland
One French company under Jakob Bourgnignon de Corobel
One French company under Pierre de la Ville
Regarding dress, it seems the infantry were in several cases provided with cloth for uniforms by the Swedish army. Either ready made jackets and trousers in Blue and/or gray or cloth for them to make their own. I would expect them all to look similar(to the Swedes) except for the Scottish (using some berets and maybe plaids).
I would expect the cavalry to be light, reiter types with small differences between the countries. I asked ChatGPT to explain potential differencies and got a response that look quite plausible:

A few images of Dutch forces 1600 borrowed by Osprey:


