Как правильно the bravest pupils (go-goes) . the most cunning pupils (go-goes) . the kindest pupils (go-goes). to slythering. harry ( go-goes) to gryffindor. pupils (work-works) .

the bravest pupils (go-мн.число  
the most cunning pupils (go-мн.число
the kindest pupils (go-мн.число to slythering.
harry (goes-ед.число to Gryffindor.
Pupils (work-мн.число