Simipour: Simipour is simply put an atrocious Pokemon. If you want to use an offensive Water type, use Greninja (and yes I know you strongly dislike it but Greninja is one of the most viable Pokemon in Nat Dex)
Greninja @ Waterium Z
Ability: Protean
EVs: 252 SpA / 4 Atk / 252 Spe
Hasty / Naive Nature
- Hydro Pump
- Hidden Power [Fire]
- Ice Beam / Spikes
- Gunk Shot
Greninja @ Groundium Z
Ability: Protean
EVs: 230 Atk / 252 Spe / 24 SpA
Hasty / Naive Nature
- Dig
- Gunk Shot
- Ice Beam
- Hidden Power [Fire] / Spikes
Greninja @ Choice Specs
Ability: Battle Bond
EVs: 252 SpA / 252 Spe / 4 Def
Timid Nature
- Hydro Pump
- Dark Pulse
- Ice Beam
- Extrasensory / Grass Knot / Spikes / Water Shuriken
Tangrowth: Tangrowth is a very good Pokemon in Nat Dex OU. However, it usually tends to lean more on the defensive side
Tangrowth @ Assault Vest
Ability: Regenerator
EVs: 252 HP / 252 SpD / 4 Def
Sassy Nature
- Giga Drain
- Knock Off
- Hidden Power [Ice]
- Earthquake / Sludge Bomb
There's also a Physically defensive pivot set
Tangrowth @ Rocky Helmet
Ability: Regenerator
EVs: 252 HP / 252 Def / 4 SpD
Relaxed Nature
- Giga Drain
- Knock Off
- Hidden Power [Ice]
- Sleep Powder
Incineroar: There is little reason to use Incineroar over Cinderace. However, Incineroar can still work in Nat Dex OU, to an extent. I know you said Incineroar is not negotiable but the Cinderace set I'm putting here is just a suggestion
Cinderace @ Heavy-Duty Boots
Ability: Libero
EVs: 252 Atk / 4 Def / 252 Spe
Jolly Nature
- Pyro Ball
- High Jump Kick
- Gunk Shot
- U-turn / Bulk Up
Incineroar @ Heavy-Duty Boots
Ability: Intimidate
EVs: 252 HP / 196 SpD / 60 Spe
Careful Nature
- Overheat
- Knock Off
- Parting Shot
- Will-O-Wisp
Ampharos: Pretty bad, as I've said before you won't find much success with a slow offensive Mon. Zapdos is faster, has Defog and reliable recovery, and has similar bulk.
Zapdos @ Heavy-Duty Boots
Ability: Static / Pressure
EVs: 248 HP / 40 SpA / 220 Spe
- Discharge / Volt Switch
- Hurricane
- Defog
- Roost
Honchkrow: Its just too slow, getting it to 1HP is too inconsistent, and too risky with Endure because of all the priority and scarfers in Nat Dex OU. Weavile is very fast but also very frail.
Weavile @ Choice Band
Ability: Pickpocket
EVs: 252 Atk / 4 Def / 252 Spe
Jolly Nature
- Triple Axel / Icicle Crash
- Knock Off
- Ice Shard
- Pursuit / Low Kick
Bronzong: There are better Steel types and Psychic types. Magearna and Slowbro are the best examples, Magearna being possibly the most terrifying wallbreaker in the metagame, and Slowbro being great defensive utility and an excellent pivot
Magearna @ Choice Specs
Ability: Soul-Heart
EVs: 252 SpA / 252 Spe / 4 HP
Timid / Modest Nature
- Fleur Cannon
- Volt Switch
- Ice Beam
- Aura Sphere
Slowbro @ Heavy-Duty Boots (Leftovers if you think you are safe enough from hazards with Defog Zapdos)
Ability: Regenerator
EVs: 252 HP / 252 Def / 4 SpD
Bold Nature
- Scald
- Future Sight
- Teleport
- Slack Off