Gyarados @ Flyinium Z
Ability: Intimidate
Level: 50
EVs: 36 HP / 252 Atk / 4 Def / 4 SpD / 212 Spe
Adamant Nature
- Waterfall
- Dragon Dance
- Bounce
- Earthquake/Substitute/Taunt/Ice Fang
Standard Fly-Z set. The speed stat allows you to outspeed greninja at +1, the rest dumped in bulk. The last move can be a variety of moves depending on what the team needs.
Gyarados @ Rockium Z
Ability: Intimidate
Level: 50
EVs: 252 Atk / 4 SpD / 252 Spe
Jolly Nature
- Waterfall
- Dragon Dance
- Stone Edge
- Earthquake/Substitute/Taunt/Ice Fang
Similar set, I've put the Rockium-Z here which is another major option, last move up to grabs. Max speed is needed to outspeed base 80s like Mamoswine.
Gyarados @ Figy Berry
Ability: Intimidate
Level: 50
EVs: 236 HP / 4 Atk / 252 Def / 4 SpD / 12 Spe
Impish Nature
- Waterfall
- Ice Fang
- Roar
- Toxic / Taunt
A defensive set with bulky berry can be used as a disruptor and wall to certain threats like mega salamence and some blaziken variants whilst having a decent lando/hippo matchup, the speed evs are for speed creeping tho max max is fine.