by breed do you species or by colour?
Basically the pet class is just that, a class for pets that does not require a NHC qualified judge to judge. the hamsters are judged on tamness, condition, and often things each judge feels is best, most give enrichment points, some give points for 'star quality'. End of the day its a bit of fun, with awards going to most, and of course higher awards to those with good tame pets in decent condition.
The main show is more formal, it takes all day for the hamsters to each be judged and they are judges to the standards set out by the NHC,
this is about the standards for syrians
NHC Exhibition Standards - Syrian - National Hamster Council
and this for the 4 other species, campbell, winter white, chinese and roborovski
NHC Exhibition Standards - Dwarf (Any Other Species) - National Hamster Council
these standard give point regarding how near the hamster is to a specified type for the species, size for it, condition, fur, and of course for the colour, hamsters are put in classes of colour and fur types, each standard colour has a standard written to which the hamster is judged, if it is a non standardized colour it is judged in the non standard class and is not given any marks for colour.
must get these videos stolen and put on the NHC site
they are great