Play Claw Fossil as if it were a Basic Pokémon. While in play, Claw Fossil counts as a Colorless Pokémon (instead of a Trainer card).  Claw Fossil has no attacks of its own can’t retreat and can’t be affected by any Special Conditions.  If Claw Fossil is Knocked Out it doesn’t count as a Knocked Out Pokémon.  (Discard it anyway.)  At any time during your turn before your attack you may discard Claw Fossil from play.

Jagged Stone:

If Claw Fossil is your Active Pokémon and is damaged by an opponent’s attack (even if Claw Fossil is Knocked Out), put 1 damage counter on the Attacking Pokémon.