How many London Paddington to Reading stopping services are there operated by GWR?
Timetable T10 - from
https://www.gwr.com/plan-journey/train-times - will provide you with an answer - look for the column header "
GW» " to find the Great Western services. It rather depend on what you call a "stopping" service - could be anything from an all stations train, through to any train that makes just one intermediate stop such as the evening 'peak' trains that call at Twyford.