You're out of line here.
Seaking cannot switch safely in on Heliolisk.
252 SpA Life Orb Heliolisk Grass Knot (60 BP) vs. 104 HP / 0 SpD Seaking: 182-216 (55.6 - 66%) -- guaranteed 2HKO
252 SpA Life Orb Heliolisk Hyper Voice vs. 104 HP / 0 SpD Seaking: 204-242 (62.3 - 74%) -- guaranteed 2HKO
And if it slaps on an assault vest, then it cannot OHKO either pokemon back.
But there IS a pokemon who can...I present to you: Assault Vest Whiscash
Whiscash @ Assault Vest
Ability: Anticipation
EVs: 172 HP/ 28 Att/ 224 SpA/ 84 SpD
Mild Nature
- Earthquake
- Scald
- Ice Beam
- filler
Lizard can't even 2HKO it with a 4x Super Effective Move:
252 SpA Life Orb Heliolisk Grass Knot (40 BP) vs. 172 HP / 80 SpD Assault Vest Whiscash: 161-192 (39.8 - 47.5%) -- guaranteed 3HKO
252 SpA Life Orb Heliolisk Hyper Voice vs. 172 HP / 80 SpD Assault Vest Whiscash: 134-160 (33.1 - 39.6%) -- 100% chance to 3HKO
Take a look at this insane power:
28 Atk Whiscash Earthquake vs. 0 HP / 4 Def Heliolisk: 306-360 (115.4 - 135.8%) -- guaranteed OHKO
28 Atk Whiscash Earthquake vs. 0 HP / 4 Def Jolteon: 272-324 (100.3 - 119.5%) -- guaranteed OHKO
And as a bonus it can still slay dragons with ease:
224 SpA Whiscash Ice Beam vs. 0 HP / 0 SpD Salamence: 324-384 (97.8 - 116%) -- guaranteed OHKO after Stealth Rock
224 SpA Whiscash Ice Beam vs. 252 HP / 4 SpD Eviolite Gligar: 252-300 (75.4 - 89.8%) -- 12.5% chance to OHKO after Stealth Rock
Scald is for the burns, although getting beaten by Almighty Catfish Lord is already the biggest burn there is.