>>32634759>low defensive stat on one or 2 sidesWhile the Alola examples I used weren't that good, having one low defense stat doesn't necessarily make a pokemon frail. Skarmory has low hp/spdef but is still a good physical wall. Chansey and Clefable have low defense, and Tangrowth is a grass type with low Sp. Def, but these are still considered bulky for their other capabilities.
I agree typing does hinder some of the mons though, and I think a big problem is that the mons with decent bulky stats also lack reliable recovery. Hopefully gamefreak will throw them a bone in later games.