You can look them up on cricinfo. The ones I have heard of are Marnus Labuschange, who has played test cricket for Australia, Marchant de Lange who has played test and limited over international cricket for South Africa, and Billy Root who has a more famous brother, although he is a decent player. Then there are a couple more Australians, and a Dutchman. Graham Wagg played for England A in that past. Not one of these would be eligible to play for Wales. Their captain, David Lloyd, is Welsh, but has never come into consideration for England (for whom of course he is currently eligible).

Glamorgan as a side are reasonably high in the Division 2 table. So precisely an average county side. If you take out overseas players though, they couldn't put 11 on the field. You would have to make up the numbers by a trawl of village sides.