Weedle is fainted and has 0/9 health.

Squirtle attacks Charmander!  Charmander took 4 damage.
Charmander is wounded and has 6/10 health.

Charmander is healed 2!
Charmander is wounded and has 8/10 health.

Jigglypuff attacks Charmander!  Charmander took 7 damage.
Charmander is wounded and has 1/10 health.

Charmander attacks Jigglypuff!  
No damage done. Jigglypuff has too strong of a defense.

Weedle cannot attack when fainted!

Squirtle attacks Charmander!  Charmander took 4 damage.
Charmander faints!
Charmander is fainted and has 0/10 health.

Charmander is fainted and cannot be healed.