A lot of people have the new American Mew and are thinking he's like
Charizard-only good for collectability.  However, I think
he's a great hoser against raindance.  He are his stats:

Mew         Basic Pokémon  50 HP

1 Psychic:  Psywave  10x
Does 10 damage times the number
of energy cards attached to the
defending Pokémon.
2 Psychic: Devolution Beam
Choose an evolved Pokémon (your own
or your opponent's). Return the highest
Stage Evolution card on that Pokémon
to it owner's hand. That Pokémon is no
longer Asleep, Confused, or Paralyzed
(just as if you had just evolved it.)

This card is not incredibly broken, but it hoses Raindance incredibly
well. Most Raindances don't run Wartortle- only Pokémon Breeder.  So they
can't re-evolve
Blastoise.  Plus Gyrados gains 70 HP when it evolves- get 30 on Gyrados and
de-evolve...
no more Magicarp!  His 1-for-up-to-630 (59 on the defender, 4 PlusPower,
yeah, I know it'll
never happen) is good to.  So use him if you fear raindance.  Or want to try
to do 630 damage.