Wigglytuff is a bad Pokemon mainly because of its mediocre stats overall, despite its high HP, which is let down by paper-thin defenses. Sylveon outclasses it in the Choice Specs Fairy role:
-Hyper Voice
-Psyshock
-Hidden Power (Fire/Ground)/Shadow Ball
-Baton Pass
Nature: Modest
EVs: 240 HP/252 SAtk/16 Spe
Item: Choice Specs
Ability: Pixilate
Aromatisse's offensive movepool is rather shallow, meaning it has difficulty doing offensive duties. Also, Choice Specs locks the user into a single move while it's in battle, meaning most status moves besides Trick are pointless. You could use an entry hazard setter on the team, as they're helpful in getting in chip damage to take down threats faster. Examples are:
Garchomp:
-Stealth Rock
-Dragon Tail
-Earthquake/Toxic
-Fire Blast/Toxic
Nature: Impish
EVs: 240 HP/176 Def/92 Spe
Item: Rocky Helmet
Ability: Rough Skin
or
-Stealth Rock
-Outrage/Dragon Claw
-Earthquake
-Fire Blast/Swords Dance
Nature: Naive/Jolly
EVs: 252 Atk/4 SAtk/252 Spe
Item: Lum Berry/Focus Sash
Ferrothorn:
-Stealth Rock/Spikes
-Leech Seed
-Power Whip/Protect
-Gyro Ball/Thunder Wave
Nature: Relaxed
EVs: 252 HP/88 Def/168 SDef
Item: Leftovers
Ability: Iron Barbs
Therian Landorus:
-Stealth Rock
-Earthquake
-Stone Edge/Rock Slide/Knock Off
-U-turn
Nature: Impish
EVs: 252 HP/240 Def/8 SDef/8 Spe
Item: Leftovers/Rocky Helmet
or
-Stealth Rock
-Earthquake
-Stone Edge/Knock Off
-U-turn/Explosion
Nature: Adamant/Jolly
EVs: 72 HP/252 Atk/184 Spe
Item: Soft Sand/Earth Plate/Focus Sash
Skarmory:
-Stealth Rock/Spikes
-Brave Bird/Counter
-Whirlwind/Taunt/Defog
-Roost
Nature: Impish
EVs: 252 HP/252 Def/4 SDef
Item: Leftovers/Rocky Helmet
Ability: Sturdy
or
-Iron Head
-Spikes
-Whirlwind/Taunt
-Roost
Nature: Careful
EVs: 252 HP/4 Def/252 SDef
Item: Leftovers
Ability: Sturdy
Heatran:
-Stealth Rock
-Lava Plume
-Toxic
-Taunt/Protect/Roar
Nature: Calm
EVs: 248 HP/192 SDef/68 Spe
Item: Leftovers
Medicham does so much better as its Mega Evolution, as it's decently fast and still hits hard. It also has a significantly stronger Fighting STAB in High Jump Kick:
-High Jump Kick
-Zen Headbutt
-Fake Out
-Ice Punch
Nature: Jolly/Adamant
EVs: 252 Atk/4 Def/252 Spe
Item: Medichamite
Ability: Pure Power
Shiftry is also a mediocre Pokemon to use. Choice Scarf paired with a ton of status moves is bad. Bisharp is a better Pokemon to pair with Medicham, as it has Pursuit to deal with Ghost and Psychic Pokemon switching out, as well as Iron Head to dispatch Fairy Pokemon:
-Sucker Punch
-Iron Head
-Knock Off
-Pursuit/Swords Dance
Nature: Adamant/Jolly
EVs: 4 HP/252 Atk/252 Spe or 204 Atk/52 SDef/252 Spe
Item: Black Glasses/Dread Plate/Life Orb/Lum Berry
Ability: Defiant
or
-Sucker Punch
-Iron Head
-Knock Off
-Pursuit
Nature: Adamant
EVs: 192 HP/220 Atk/96 Spe
Item: Assault Vest
Ability: Defiant
The best Tangrowth can offer in standard play is Assault Vest with a specially defensive spread to patch its bad special bulk. However, you do need something that deals with Talonflame if you didn't go for Heatran, bulky Garchomp or Therian Landorus. Wash Rotom can deal with Talonflame nicely:
-Volt Switch
-Hydro Pump
-Will-o-Wisp
-Pain Split/Rest
Nature: Bold
EVs: 248 HP/252 Def/8 Spe
Item: Leftovers/Chesto Berry
Snorlax isn't as good as it used to be from R/B to D/P. If you want another bulky attacker, an example is Dragalge:
-Sludge Wave
-Draco Meteor
-Focus Blast
-Toxic Spikes/Scald
Nature: Modest
EVs: 228 HP/252 SAtk/28 Spe
Item: Black Sludge/Choice Specs
Ability: Adaptability