Weavile is weak to fire, fighting, bug, rock, steel, and fairy. That is 6 weakness and one is x4 (Fighting).
Prankster
Prankster ability is very used for this situations. Why? Setting up a Will-o-Wisp for Attack's drop or an annoying Thunder Wave. Also Prankster can be good to induce weather but I will talk about that later.
Thunder Wave is very useful for this or Confuse Ray.
Thundurus and Sableye are great for this strategy.
Light Screen + Reflect combo
Not the best combo ever but it can do alot of resistance on your Weavile.
Klefki is the most common for this, having Prankster and also learning a STAB Moonblast and Thunder Wave.
Klefki @ Light Clay
Calm or Bold
EVs - 252 HP / 252 Sp.Def
- Reflect
- Light Screen
- Thunder Wave
- Moonblast
Follow Me
Pachirisu is a great Follow Me user. Why this move? You can set a Swords Dance in your Weavile and since Weavile has alot of Speed, it can strike hard with some great STAB moves.
Pachirisu and Togekiss are great users. Also Togekiss was a 60% to flinch with following moveset.
Pachirisu @ Leftovers/Focus Sash
EVs - 252 HP / 252 Sp.Def / 4 Speed
- Follow Me
- Thunder Wave
- Thunderbolt
- Any move
Togekiss @ Leftovers
Modest
Serene Grace
EVs - 252 HP / 252 Sp.Atk / 4 Speed
- Air Slash
- Flamethower
- Aura Sphere
- Follow Me
Snow Warning
Hail can deal damage, since Weavile is a Ice-type it won't get hurt, so you can put a Snow Warning to activate the hail.
Abomasnow is the most obvious for this one.
Abomasnow @ Life Orb/Choice Band
EVs - 252 HP / 252 Atk
Adamant Nature
Snow Warning Ability
- Earthquake
- Ice Shard
- Wood Hammer
- Rock Slide
Talonflame
Can deal with fighting and steel very easily, with a Life Orb and a perfect speed, it can be very useful with Weavile.
Talonflame @ Life Orb
Jolly / Adamant
Gale Wings
EVs - 252 Atk / 252 Speed
- Brave Bird
- Flare Blitz
- Roost
- Swords Dance / U-Turn
Aerodactyl
Aerodactyl has a INCREDIBLE power and a high speed. It can deal with all Weavile's weakness with this moveset.
Aerodactyl @ Life Orb
Adamant / Jolly
EVs - 252 Atk / 252 Speed
- Earthquake
- Stone Edge / Rock Slide (Stone Edge accuary isn't the best, so Rock Slide if you want)
- Iron Head
- Fly / Aerial Ace