I think you screwed up a bit then.
Ditto has a BST of 288 and Slakoth 280 which are greater than combee's 244
Also shedinja and azurill both have BSTs less than combee and are not on the list
azurill has a BST of 190 and shedinja has a BST of 236
Azurill should have been on the list.
As for Shedninja, it has wonder guard.
And Ditto's on the list because it's ditto, its self explanitary and in the end its gonna have the same stats as the rest.
Slakof is on because it's ability is bad enough to be put there for interesting teams.