This is fairly doable solo with the right partners:
Meowscarada @ Shell Bell
Ability: Overgrow
Tera Type: Grass
EVs: 252 Atk
- Knock Off
- Flower Trick
- Seed Bomb / Grassy Terrain / filler
- Hone Claws / Mud-Slap / Chilling Water / filler
1 - Start with Knock Off to remove its Light Ball
2 - Attack with a weak move until the Tera Orb is charged (Mud-Slap seems nice to reduce its accuracy)
3 - Activate Tera
3 - Keep attacking with Flower Trick (note that its 10 PP might NOT be enough) / Seed Bomb
I won with just Knock Off, Flower Trick and Seed Bomb; the rest are ideas I had which might be interesting to try.
Being Grass-type it naturally resists both Water and Electric, though Thunder can still paralyze (I was lucky enough to get only one full paralysis).
My partners included Arcanine (Intimidate + weak to Water, which means it gets to trigger several times) and Toxapex (has Chilling Water), which helped reduce Meowscarada's initial weakness to Play Rough. I guess Arboliva would have helped.
I used the standard offensive spread I had ready (Jolly / 252 Atk / 252 Spe) to avoid wasting resource, but Meowscarada should be fast enough to outspeed Pikachu uninvested so a bulky spread would likely be better (I guess Adamant / 252 HP / 252 Atk).
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This is another COMPLETELY UNTESTED idea which might or might not be useful:
Gardevoir
Ability: Trace
Tera Type: Grass
- Knock Off
- Energy Ball
- Calm Mind / Light Screen / Reflect / Magical Leaf / Sunny Day / Life Dew / Stored Power
I just note this because of Knock Off + Trace to copy Lightning Rod, but I doubt it takes Iron Tails too well.