For the Britsish swiss the following was abridged from "From Foreign Regiments in the British Army 1793-1802 – Notes on each Corps or Regiment" by C T Atkinson. Despite the title it does cover up to the end of the Napoleonic Wars – the notes are very extensive on each unit, covering their service record etc.
Don't forget de Roll's which was the first Swiss corps taken into British service and almost the last foreign corps to be disbanded.
Lord Bentinck writing from Sicily in 1813, spoke highly of De Roll's, describing it as better than one battalion of the King's German Legion then under his command, and its record as to desertion, the curse of foreign corps, compares very favourably with those other units. In 1812, for example, when 101 men deserted from Dillon's, De Roll's only lost 18 to this cause. [Note Dillon's was an Irish regiment]
In addition it would appear that the British paid for three other Swiss units (Bachmann, Roverea & de Salis) who served in 1799/1800.
De Meuron's – of the two thousand odd men who served under the British flag, nearly a third were Swiss, with 500 Germans, nearly 300 Dutch, and 200 Alsatians. Its desertion record was far better than most of the foreign corps and would compare quite favourably with those from some British regiments.
De Watteville's – its muster rolls show a good number of Slavonic names, but very few French or Italian, and it does seem the regiment did its best to maintain its Swiss character and to avoid having its ranks filled with up with recruits from every nation. There is evidence that like other Swiss corps, it did preserve a much higher level of discipline and efficiency and trustworthiness than most of the foreign units in British service. De Watteville lost to desertion: 17 men in 1811; 26 in 1812; and 30 in 1813 (considerably less than Dillon's or the Brunswiock Oels).
A useful booklet on the Swiss in Spanish service is "Presencia suiza en la milicia española. Nº 6" PDF link Although in Spanish it does say:
" The majority of the Swiss military served Spain against the French invaders in the War of Independence. From the six Swiss regiments of the Spanish Army, only the regiment number 5 Traxler and number 6 Preux were in the service of France, although they had many deserters who joined the Spanish rebels. Those Swiss regiments had an outstanding performance during the war and fought squarely in the Spanish army like any other unit. After the war, the Swiss regiments began disappearing. In 1823, they ended their employment in the Spanish army. Then three Swiss regiments were restored in 1824 and finally, in 1841, they were dissolved."
The entry for generic Swiss, that rates "Landwehr" is I believe for the units of the Swiss Confederation Army (probably a bit harsh in my view).
