Do you mean Spanish troops? I don't recall Prussians being specialized in light infantry/guerilla tactics. I think you have the two nations mixed.To be fair Spain didn't specialize so much as kinda gave people in the hills weapons. The Silesians are the only example I can think off. The Friekorps where must mercenary troops and Landwehr where just militia.
There were no armies specialized in guerrilla warfare at that time. There were partisan groups that operated for the various Spanish and Portuguese Juntas during the Peninsular War, who were called guerrilleros
and their actions were later called guerrilla
(little war). The Silesians werent trained in guerrilla warfare, they did the same job as most of the sharpshooter units in the period. To cover flanks, skirmishing, fighting in hard terrain (woodland, highland, etc) and take light defended strategic positions (bridges, small fortified positions, etc.).