All Stat Reducing Moves are prevented by White Smoke and Clear Body
*Hyper Cutter protects from decreased Attack stat only
Defiant boots a Pokemon's Attack when any stat is decreased, and this has the side effect of not allowing their Attack to be decreased.
Speed Boost Pokemon can still have its Speed decreased, but it won't be long before it is back to normal (or faster than normal), so it is protected from Speed drops, in a fashion.
$tarfire also reminded me of two more:
Big Pecks protects from its Defence being lowered.
Keen Eye prevents its accuracy being lowered.
As for preventing statuses:
Water Veil protects from Burn
Limber protects from Paralysis
Vital Spirit and Insomnia protect from Sleep
Magma Armor protects from frozen
Immunity protects from Poison
Oblivious protects from Attract
Own Tempo protect from Confusion
Poison Heal will heal the Pokemon when it is poisoned
Magic Bounce will reflect any status move back at the attacker, but doesn't protect from statuses, per se as it can still be affected by moves with a chance to inflict a status
Magic Guard allows the Pokemon to be inflicted with a status, but it won't lose health from being Poisoned or Burned.
Natural Cure - it can still be inflicted with a status, but it will be healed when it switches out
Here are another couple $tarfire added:
Hydration cures statuses while it is raining.
Leaf Guard cures statuses while it is sunny.
Inner Focus protects from flinching.
I think that is everything - if I missed something let me know in the comments, and I will add it into my answer.