Defense Walls

Milotic

Milotic can be a very effective wall because of its high HP and Sp. Defense, along with a strong Defense. IVs should exclude Attack, and EVs should be invest fully in HP, and scattered around Defense, Sp. Defense, and Sp. Attack. The ability Marvel Scale is recommended, especially if Rest/Sleep Talk is ran, since it can buff Milotic's defense. The item should be Leftovers to recover health, and the nature should be Clam or Bold.

This is a standard Milotic moveset. Having Scald and Ice Beam do have decent coverage, and Scald give a good chance to deliver burns. For Rest and Sleep Talk, it is always important to use an actual move after two turns of sleep, for Milotic will likely wake up. For Recover and Toxic, it is a stalling combo to whittle down your opponent's health while being healthy yourself.

Move 1: Scald	Move 2: Ice Beam
Move 3: Recover/Rest	Move 4: Toxic/Sleep Talk

Umbreon

Umbreon is another popular option because of its very high defenses and HP. Umbreon should be invested in HP and Sp. Defense for the ultimate defense, and a little bit in Defense. The defense can be raised by Curse. Leftovers is probably the best option as well to regain health. IVs should only lack Sp. Attack, and Careful should be its nature, but Impish can work as well.

This set is utlizing Umbreon's tanky defenses to endure attacks while setting up. Because of its already meager Speed, the speed drop from Curse is not a big deal, and it buffs Attack and Defense. This builds up Payback, which doubles in power if it moves after the opponent. Moonlight is to recover additional health. The last slot should be status related, whether it's whittling your opponent down, or healing statuses of your own.

Move 1: Payback	Move 2: Curse
Move 3: Moonlight	Move 4: Toxic/Heal Bell/Confuse Ray

Dusknoir

Dusknoir's role is very similar to Umbreon's. It has high Defense and Sp. Defense, but also has reliable Attack Stat. Dusknoir's Ability should be Pressure to subtlely burn away opponent's PP, and its item is Leftovers. EVs should be spread throughout HP, Defense, Sp Defense, and Attack, and the nature can be Impish or Careful.

Dusknoir can be either a giant staller, or more on the offensive side. To stall, Night Shade should be used to always to a set amount of damage, and Protect is to stall out PP and the burn or poison. For more offense, Shadow Punch is a reliable STAB move that always hits, and Earthquake is for coverage. Will-O-Wisp is recommended more because it also lowers the opponent's Attack, in which case Sp. Defense should be invest in more with EVs. Pain Split is to recover some health.

Move 1: Night Shade/Shadow Punch	Move 2: Protect/Earthquake
Move 3: Will-O-Wisp/Toxic	Move 4: Pain Split