Question

I am thinking:

Fake Out: Priority.

Overheat: Massive STAB damage.

Toxic: Gives the foe bad poison, so that Chimchar is still causing trouble evn though it was defeated in only a few turns.

Protect: To help Chimchar survive for longer. Works with Toxic.

Answer 1

How about this?

Physical:

Thunderpunch(egg)-covers water weakness

Blaze Kick(Egg)/fire punch-STAB, good power

swords dance(TM)/fake out-powers him like crazy, or fake out, since it is LC.

brick break(TM)/vacuum wave-cover rock weakness, VW is priority, making it even better.

special:

Heatwave/flamethrower/fire blast/overheat-Your choice, heatwave is in the middle for power and has no bad secondary effects like overheat, (I like overheat since chimchar will only last a little while anyway. Plus using overheat after blaze activates is fun.)

Grass knot/hidden power (grass)-both moves cover all of chimchar's weaknesses. if you can't get hidden power, grass knot works too. Unfortenately, since the little cup pokemon are typically small, grass knot loses it's charm, which is why hidden power is probably the better option.

taunt-force the foe into attacking. good for breaking your opponent's walls.

Fake out-I know it's physical, but this is LC.

Other good moves:

counter
magic coat
endeavor
bulk up
stealth rock

Answer 2

Chimchar, All Right:

Mixed Sweeper:
Brick Break/Aerial Ace: POWERFUL Move that takes Down Rock:) or Aerial Ace For Surprise

Flamethrower/Heat Wave/Fire Blast/Blaze Kick/Fire Punch/Overheat: STAB

Thunderpunch: Good Coverage of Water, and Flying.

Grass Knot/Hidden Power(Grass)/Iron Tail/Swords Dance: For Stat Boosting, or Weaknesses. Iron Tail Will Take Down Those Annoying Rock/Ground Types, and Hidden Power Grass and Grass Knot Are Great Coverage.