There are many weaknesses in your team. Forretress is OK, so lets start with Hippowdon. Since Forretress already has stealth rock, replace Hippowdon's Stealth Rock with Earthquake.
Stoutland's moveset needs a lot of help. Return can stay. Replace the other moves with Crunch, Thunder Wave, and Wild Charge. Thunder Wave is to cripple the opponent. Instead of choice band, give it life orb.
With Substitute, choice scarf is pretty useless. Replace choice scarf with Life Orb or leftovers. You might want to try this set:
EV's: The ones you already have
Dragon Dance is there to increase Dragonite's sweeping potential. Outrage is there since it is a STAB move and can deal a high amount of damage. Earthquake covers its rock weakness. Extreme Speed is to revenge kill while substitute makes it more defensive. Leftover recovers the damage caused by sandstorm.
You might want to try this set for Shuckle:
This set is to stall. Rest recovers damage, toxic poisons the foe, protect helps to stall longer, and encore is there to troll the opponent. Leftovers recovers health more.
Chansey's set is good. No changing here.
Well that's my advice. Overall, I give your team a 6/10. Follow my advice and it could become a 10/10 possibly. Hope I helped!
Lord of Reptiles