Grass Knot!
Grass Knot is the better choice, it hits bulky water types like Seismitoad. Grass Knot also hits bulky Rock types like Regirock. And after some Nasty Plots, Grass Knot will be extremely powerful.
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Simisear @ Life Orb
Trait: Blaze
EVs: 4 HP / 252 SpA / 252 Spe
Timid Nature (+Spe, -Atk)
- Nasty Plot
- Grass Knot
- Flamethrower
- Hidden Power [Rock]