The answer to this is really simple...don't ask yourself, "Who's the
better Pokemon in the TCG?"  Are you implying who is the best attacker?
Or who would win in a head-to-head situation?

Chansey is bar none the best Pokemon card in the game.  Why?  He can go
in ANY deck.  Charizard can also do this courtesy of his Pokemon Power
and colorless attacks of his lesser evolution forms.  Chansey's
versatility of being a WALL or an incredible ATTACKER should not be
overlooked.  Who has resistance to colorless?  Nobody does...Chansey is
the one card that when your deck is weak against something, he can come
out and really hurt the other deck's big guns.

Keith