Weird art. Hee.
HP 90. Not the amazing 120 of the original but she's staying put.
Sing: status and something disabling, good stall.
Egg Surprise: Healing yourself or damaging the opponent. If the luck is slanted, it could turn on you with one effect and not the other.
Energy cost: Fits Any deck.
Retreat cost: Two, but given Chansey's lack of speed, not surprising.
Overall, a good staff card that can dish out as well as take it. 8/10.