
Aerodactyl
@Leftovers
Ability: Pressure
Nature: Jolly
EVs: 252 HP/6 ATT/252 SPEED
Purpose: PP Drainer/Annoyer
>Substitute
>Protect
>Rock Slide
>Fly
Aerodactyl is never really thought of as a tank-ish Pokemon, but this set actually works very well! The point is to drain the opponent's PP of moves like Stone Edge, Draco Meteor, Water Spout (etc)... Sub/Protecting provides time for the Leftovers to work and Fly stalls even more. Rock Slide for the good chance of flinch and a nice STAB move. Very annoying and very effective!

Swellow
@Flame Orb
Ability: Guts
Nature: Jolly
EVs: 6 HP/252 ATT/252 SPEED
Purpose: Phys Sweeper
>Protect
>Facade
>Brave Bird
>Quick Attack
Typical Swellow- Protect first, then sweep away as long as it moves first. U-turn if it can't handle something.

Jolteon
@Focus Sash
Ability: Volt Absorb
Nature: Timid
EVs: 6 HP/252 SP ATT/252 SPEED
Purpose: Spec Sweeper
>Thunderbolt
>HP Grass
>Wish
>Baton Pass
Super fast and good sp attack. Use Tbolt for STAB and HP Grass for Swampert or Rhyperior. Focus Band keeps it alive one extra turn and provides time for Wish/Baton Pass if things get rough.

Cresselia
@Leftovers
Ability: Levitate
Nature: Bold
EVs: 252 HP/252 DEF/6 SP ATT
Purpose: Phys Tank
>Ice Beam
>Charge Beam
>Rest
>Sleep Talk
This set can last for quite a long time. Boost special attack and just go to sleep whenever inflicted with a status or injured.

Clefable
@Leftovers
Ability: Magic Guard
Nature: Bold
EVs: 252 HP/152 DEF/102 SP DEF
Purpose: Tank/Status Switch-in
>Flamethrower/Ice Beam
>Cosmic Power
>Wish
>Protect
Even though it has unimpressive stats, this thing can be an absolute beast after a few Cosmic Powers. Wish/Protect to stay alive and Flamethrower/Ice Beam to attack and no worries from Taunting.

Glaceon
@Choice Scarf
Ability: Snow Cloak
Nature: Timid
EVs: 6 HP/252 SP ATT/252 SPEED
Purpose: Surprise Spec Sweeper
>Ice Beam
>HP Fighting
>Shadow Ball
>Blizzard
The Choice Scarf catches a lot of opponents off-guard, and provides Glaceon w/ a nice speed of 377, outrunning anything with a base speed of 120 or less. HP Fighting is helpful for steels and Shadow Ball for Slowbro. Blizzard is somewhat of a filler in case it is hailing.