Here are what I believe to be the best of each type
Normal: Braviary is chosen because of Marshals Fighting types.
Braviary Lvl. 80+
Item: Choice Band/Muscle Band/Leftovers
Jolly Nautre
Ability: Doesn’t matter, Defiant if possible
- Brave Bird/Fly
- Return
- Superpower
- Shadow Claw
Braviary is unfortunately a White 2 Exlcusive however, so as a substitute here is an Unfezant set.
Unfezant Lvl. 90+
Item: Choice Band/Muscle Band
Adamant Nature
Ability: Super Luck
- Fly
- Return
- U-Turn
- Roost/Steel Wing
Flying: Archeops is good, but don’t let it go under half its HP.
Archeops Lvl. 80+
Item: Choice Band
Adamant Nature
Ability: Defeatist
- Rock Slide
- Fly
- Crunch
- U-Turn
Bug: Crustle has good typing for the E4.
Crustle Lvl. 80+
Item: Choice Band
Adamant Nature
Ability: Shell Armor
- X-Scissor
- Shadow Claw
- Earthquake
- Aerial Ace
Rock: Archeops again.
Grass: Whimsicott has good move type diversity and speed.
Whimsicott Lvl. 80+
Item: Choice Specs/Leftovers
Modest Nature
Ability: Prankster/Infiltrator
- Giga Drain
- Psychic/Hurricane
- Shadow Ball
- Stun Spore/U-Turn/Leech Seed
Dark: Hydreigon, I left a set in the comments
Dragon: Hydreigon again.
Ghost: A tough region for the Ghost type, I think Chandelures, 140 Special Attack can get through.
Chandelure Lvl. 80
Item: Leftovers
Modest/Bold Nature
Ability: Flame Body
- Flamethrower/Heat Wave
- Shadow Ball
- Psychic
- Will O Wisp
Just power your way through Grimsley with Flamethrower.
Fire: Darmanitan is very powerful.
Darmanitan Lvl. 80+
Item: Life Orb/Choice Band
Adamant Nature
Ability: Sheer Force
- Fire Punch
- Hammer Arm
- Zen Headbutt
- Earthquake/U-Turn
Ground: Excadrill has a nice dual typing that helps it resist dragon, psychic, dark and ghost! Just make sure to brute force your way through Marshal though with Earthquake.
Excadrill Lvl. 80+
Item: Choice Band
Adamant Nature
Ability: Sand Force
- Earthquake
- Brick Break
- Rock Slide
- Shadow Claw
Steel: Excadrill again, though Lucario could probably solo well too.
Lucario Lvl. 80+
Item: Choice Specs
Modest Nature
Ability: Inner Focus
- Aura Sphere
- Shadow Ball
- Psychic
- Dragon Pulse
Fighting: Lucario again.
Psychic: Metagross. I probably don’t need to explain why.
Metagross Lvl. 80+
Item: Choice Band
Adamant Nature
Ability: Clear Body
- Meteor Mash
- Zen Headbutt
- Brick Break
- Earthquake
Water: Samurott due to its good type diversity, and high offensive stats.
Samurott Lvl. 80+
Item: Choice Specs.
Modest Nature
Ability: Torrent
- Scald
- Ice Beam
- Air Slash
- Hidden Power Fighting/X-Scissor
Ice: Lapras has good typing and move diversity that makes it a good candidate for the best Ice type for the Unova E4
Lapras Lvl. 80+
Item: Choice Specs/Leftovers
Modest Nature
Ability: Shell Armor
- Ice Beam
- Psychic
- Signal Beam
- Thunderbolt
Electric: Not the best choices, but I think Galvantula can preform well.
Galvantula Lvl. 80+
Item: Choice Specs.
Modest Nature
Ability: Compound Eyes
- Thunder
- Bug Buzz
- Energy Ball
- Discharge
Posion: There are no really good poison attackers before Gen 5, but Crobats solid.
Crobat Lvl. 80+
Item: Choice Specs
Modest Nature
Ability: Inner Focus
- Air Slash
- Sludge Bomb
- Shadow Ball
- Heat Wave
Alright, that’s all of them, please tell me if you think these did well, or if there are any issues, moveset wise, or if there’s a better Pokémon.