Battle Moveset

A Good Moveset for Nosepass would have to be this:

Attacks:

Thunder Wave
Explosion
Rock Slide
Earthquake

Items Attached:

Leftovers

Preferred Nature:

Adament

Strategy Using Nosepass

Really, if you intend to use Nosepass then good luck to you. This pokemon has the worst attack(its the same as wurmple) and special attack to work with. Its defenses, however are good, but this is useless since it has no attacks to worth with its defenses.
Adamant was chosen for its nature since Explosion is the main attack it will be using, which relies on attack strength.
Max the EV's in attack stats for the same reason as above, and the rest split into the defenses, it will survive enough hits to use explosion so thats a bonus. Thunder wave is to paralyse your opponent and then use explosion to deal damage to your opponent, but don't be too surprised if your opponent's pokemon is still not knocked out.
Rock slide and Earthquake will probably not be used, and it really shouldn't be used either, these are just fillers. Use them if you feel like your opponent has made a mistake while battling and they may be useful. Other than that, I wouldn't suggest you use them.
The Idea of this moveset is to paralyse and explode, simple.
You could make this pokemon an annoyer with the attacks Toxic/attract/Rest/filler holding a chesto berry but then again, this pokemon has poor speed which is often vital within battles. Overall, this pokemon has poor attack/special attack/speed/HP and high Defenses. Nosepass has a small movepool and it doesn't learn counter either, which could've proved useful on this pokemon

EV Corner:

Max out the EVs in Attack for Nosepass with any remaining in Defense & Special Defense

Strategy Against Nosepass

Nosepass's Defenses are both high but it's Special Defense is lower, so if you attack with Water & Grass type attacks it'll be gone in no time

Contest Moveset

A good Contest Moveset for Nosepass would have to be this for the Tough Contest best with Impish, Lax, Relaxed or Bold Nature:

Attacks:

Harden
Earthquake
Sandstorm
Rock Slide

Items Attached:

Yellow Scarf

Strategy Using Nosepass

If you do the attacks in this following order you should have very few problems; 1st - Sandstorm, 2nd - Rock slide, 3rd - Harden, 4th - Earthquake, 5th - Rockslide

Locations in Games

Ruby/Sapphire Break Rocks in Granite Cave Colosseum Trade From R/S Fire Red/Leaf Green Trade From R/S

Animé Appearences

Nosepass has had several Animé Appearence. It was under the control of Roxanne at the Rustboro City Gym. She used it in her battle against Ash and occured in Flashbacks to that battle ever since! Episode 292: Winner By A Nosepass! Episode 295: Sharpedo Attack! Episode 351: Showdown! Fishing Master & The Giant Whiscash!