Battle Moveset

A Good Moveset for Kabuto would have to be this:

Attacks:

Rock Slide
Confuse Ray/Rain Dance
Aerial Ace
Return

Items Attached:

Liechi Berry

Preferred Nature:

Adamant

Strategy Using Kabuto

Kabuto is an okay pokemon, its attack strength and defense strength isn't too bad. However, it has poor special stats. Let me explain its weaknesses first:
It has a 4x weakness to grass pokemon, so watch out for sunny beamer's, however Aerial ace covers a majority of grass pokemon. It also has a weakness to fighting types too, and again Aerial ace covers this weakness.
Due to being part water, Kabuto has no weakness against ground types, and that ever so popular move: earthquake. However, don't use physical attacks to defeat Kabuto, just hit it with a special move that does normal damage or super effective damage and it should be defeated.
The best ability on Kabuto, in my opinion, would be Swift swim. This double's its speed in rain, and if you wish, you could put rain dance on this pokemon instead of Confuse Ray. It may not be as strong as its evolution(which is also able to learn swords dance), but it still has slightly below average attack strength.
The weaknesses mentioned above don't apply to the pokemon that have brick break, but are not fighting types themselves.
Kabuto can't really use any other moves that well, it could be an annoyer since it can take physical attacks more so than special attacks, allowing it to do some annoyance before its defeated.
The EV's are to increase its speed, attack and defense, EV's in other stats would be a waste. For example, Special defense, it already has poor special defense and even with EV training, its still going to suck.
The adamant nature benefits Kabuto's attack and Liechi berry boosts its attack too.
Overall, Kabuto isn't such a bad pokemon but I prefer its evolution since its stats are higher and learns a wider range of moves

EV Corner:

Max out the EVs in Attack & Speed for Kabuto with any remaining in Defense

Strategy Against Kabuto

Kabuto's Defense is strong but his Special Defense is weak. So attack with Special attacks and Super Effective Attacks such as Grass and it'll be down in no time

Contest Moveset

A good Contest Moveset for Kabuto would have to be this for the Beauty Contest best with Modest, Mild, Rash or Quiet Nature:

Attacks:

Hail
Ice Beam
Blizzard
Water Pulse

Items Attached:

Blue Scarf

Strategy Using Kabuto

If you do the attacks in this following order you should have very few problems; 1st - Hail, 2nd - Ice beam/Blizzard, 3rd - Hail, 4th - Ice beam/Blizzard, 5th - Water pulse

Locations in Games

Ruby/Sapphire Trade from FR/LG Colosseum Trade from FR/LG Fire Red/Leaf Green Revive The Dome Fossil

Animé Appearences

Kabuto has had a couple of Animé Appearences. First it attacked Ash when Ash woke it up trying to stop Team Rocket from Blowing the Canyon up. After that, Ash & Co. found an entire island made of Kabuto. Episode 013: Mystery At The Lighthouse! Episode 046: Attack of the Prehistoric Pokémon! Episode 091: Shell Shock! Episode 293: Stairway To Devon!