My favorite defensive core right now is Mawile and Grumpig. Even though both are extremely unorthodox, Mawile walls some of the prominent threats in this meta such as Cinccino, Swellow, Zangoose if it has something to take on a Close Combat, and Skuntank. Grumpig can take on most special attackers well and Thick Fat allows him to resist Fire type attacks that Mawile fears. Add Haunter to the mix and you have a great core. I haven't been seeing many Haunter in this meta even though it is amazing. It is immune to 3/4s of Zangoose's movepool and can easily disrupt many popular defensive and offensive cores with SubDisable. His biggest threat is Cinccino since it can basically OHKO him even behind a sub which I guess is the decline of his usage. I've used this core to great success on one of my teams. Btw Beheeyem is too powerful. I haven't faced one yet but after seeing what it did to cbb's Regirock, I'm afraid. Can people start using Fraxure? Any set (CB or DD) is amazing right now, but I haven't even played against one in the past two weeks.