A lot of the grooming of short-haired guinea pigs is done by the guinea pig itself, or by their guinea pig friends. All that needs to be done by their owners is a cleaning of the grease gland, (see Guinea Pig Grooming) a regular bath and a brief brush through every so often in the direction in which their hair grows. This can be done when you hold your guinea pigs, or after their regular health-checks.
Breeds with short hair won't need as much grooming as their long-haired friends
If you notice that your guinea pigs’ fur is getting quite untidy, then be sure to check them thoroughly for health problems, then perhaps increase the frequency with which you brush them.