Battle Moveset

A Good Moveset for Sceptile would have to be this:

Attacks:

Dragon Claw
Leaf Blade
Crunch
Hidden Power Fire OR Toxic

Items Attached:

Petaya Berry

Preferred Nature:

Timid/Modest

Strategy Using Sceptile

The first thing I noticed about Sceptile is its high speed and special attack.
Sceptile's movepool is quite decent as well, and can be used as a Annoyer, Special sweeper or Physical sweeper (even though this is much weaker than the special sweeper)
Leaf blade is probably the best move(aside from a sunnyday/Solarbeam combo) it can learn for its special sweeping moveset, since its base power is 105 after the increase from STAB, with a high chance of a critical hit.
Crunch, Dragon claw and HP Fire (or water if you want to cover its fire weakness, or HP Electric if you want to cover its flying weakness) are for sweeping purposes.
Toxic (or possibly Leech seed) could be used in replace of Hidden Power. Sceptile has certainly been given a much more varied movepool than most grass pokemon.
Nothing much else can be said about Sceptile, take note of the EV placements as they will increase the stats he will be using the most. With 120 base speed, you may find that you do not need the timid nature so go with modest.
If you think that Sceptile doesn't need an increase in Speed or special attack via an attached item, you might want to give it a lum berry to prevent any potential status damage

EV Corner:

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

Strategy Against Sceptile

Sceptile' Defenses are about average but it's Physical is lower so a Physical Volley or a Fire/Ice Volley should work.

Contest Moveset

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

Attacks:

Swords Dance
Rock Smash
Rock Slide
Crunch

Items Attached:

Yellow Scarf

Strategy Using Sceptile

If you do the attacks in this following order you should have very few problems; 1st - Swords dance, 2nd - Rock smash, 3rd - Rock slide, 4th - Crunch, 5th - Rock smash Locations in Games

Ruby/Sapphire/Emerald Evolve Grovyle Colosseum Trade from R/S/E Fire Red/Leaf Green Trade from R/S/E

Animé Appearences

Sceptile has yet to make an Animé Appearence. As soon as it does it will be added here