Shuckle is a terrible Pokemon to use in the current metagame ): Sure it gets a nice special defense in the sand, and it has 230 in both defensive stats, but crappy offensive moves, speed and Hp really hinder it. Shuckle is also taunt bait, and wrap isn't going to do a lot of damage, it can be phazed out, destroying your wrap strategy. Dragon Dance Gyarados can wreck this team, and so can Landorus and Terrakion, I suggest replacing Shuckle with Jellicent, it gives you a nice water immunity and takes away one of your water weaknesses. It also has synergy with Excadrill, it can take Fighting/Water moves for it, and Excadrill can take Electric/Ghost/Dark attacks.
Jellicent @ Leftovers
Trait: Water Absorb
EVs: 252 HP / 172 Def / 84 Spe or 252 HP / 252 Def / 6 SpD
Calm Nature (+SpD, -Atk) / Bold Nature (+Def, -Atk)
- Scald / Surf
- Recover
- Taunt / Shadow Ball / Ice Beam
- Toxic / Will-o-Wisp / Taunt
Latios could replace Nidoking as a special sweeper, it also takes away a ground weakness and gives you a nice immunity to it as well.
Latios @ Life Orb
Trait: Levitate
EVs: 6 HP / 252 SAtk / 252 Spd
Timid Nature (+Spd, -Atk)
- Draco Meteor
- Surf
- Hidden Power [Fire]
- Recover / Psyshock