Felancius's first VGC19 team

Tapu Koko @ Assault Vest
Ability: Electric Surge
Level: 50
EVs: 188 HP / 52 Def / 4 SpA / 108 SpD / 156 Spe
Timid Nature
IVs: 0 Atk
- Volt Switch
- Nature's Madness
- Electroweb
- Thunder

Meant to help with terrain control, sleep prevention, and can hit hard under the rain. Being a speed demon itself also can be helpful against opposing Kyogre, given the bulk it has can allow it to use Electroweb to lower speed after a Water Spout. Nature's Madness also works as a way to hit Dialga and Steel-types, and just support teammates altogether.

Hitmontop @ Eject Button
Ability: Intimidate
Level: 50
EVs: 252 HP / 164 Atk / 12 Def / 76 SpD / 4 Spe
Careful Nature
- Fake Out
- Close Combat
- Feint
- Wide Guard

3 for 1 role with Wide Guard, Fake Out, and Intimidate support. Pairs extremely well with any Kyogre set as it can fulfill many great things alongside it, either by stopping a Geomancy with Fake Out, allowing set-up with fake out pressure (Which I plan to have when Moon Series comes along), protect teammates from opposing Kyogre, and breaking opposing Wide Guards with Feint. Eject Button allows for Intimidate recycling, but can also be replaced with a berry for longevity.

Kyogre @ Choice Scarf
Ability: Drizzle
Level: 50
EVs: 76 HP / 4 Def / 156 SpA / 20 SpD / 252 Spe
Modest Nature
IVs: 0 Atk
- Water Spout
- Origin Pulse
- Ice Beam
- Thunder

Most Min-Max with Scarf Kyogre, but I opted to add a little bulk so that it can last longer. Had also considered a TR variant that might use for the typical sacrificing of Speed for Bulk as I had done with mons in VGC17 (with Garchomp) and VGC18 (With Metagross).

Dialga @ Wiki Berry
Ability: Pressure
Level: 50
EVs: 252 HP / 252 SpA / 4 SpD
Quiet Nature
IVs: 0 Atk
- Earth Power
- Flash Cannon
- Trick Room
- Thunder

I had deeply considered Xerneas, Yveltal, Groudon, and Rayquaza for this, but I chose Dialga due to how much it can cover, and even counter Geomancy Xerneas and Choice Scarf Kyogre, both of which are super common now. Hitmontop can cover the Groudon weakness as well, and a berry allows longevity. May use again in Moon Series, given Draco Meteor and Flash Cannon can allow for overkill Z-moves.

Ferrothorn @ Leftovers
Ability: Iron Barbs
Level: 50
EVs: 252 HP / 228 Atk / 28 SpD
Sassy Nature
IVs: 0 Spe
- Gyro Ball
- Power Whip
- Leech Seed
- Protect

Chose this over Celesteela due to lacking an Electric weakness and resisting both Water and Fairy, along with Primal Kyogre not being legal yet. Not much bulk needs to be added to be a good wall against common legendaries while not being named Celesteela or Mantyke (lol semi-viable memes). Leech Seed also is even more powerful in this meta due to how much it saps from bulky legendaries.

Incineroar @ Iapapa Berry
Ability: Intimidate
Level: 50
EVs: 236 HP / 4 Atk / 4 Def / 236 SpD / 28 Spe
Careful Nature
- Fake Out
- Knock Off
- Flare Blitz
- Snarl

An Alternative to Hitmontop and works better against Tapu Lele, Specially-based Legendaries, Ho-Oh, and Steel-types. While he lacks wide guard, fake out and intimidate support make it an excellent 2 for 1 support pokemon, 3 for 1 if you count knock off support. Snarl also increases the intimidate support as it affects Special Attackers harshly, giving teammates an advantage.