The Pichu and Charizard are indeed more common to find than the others. This was also mentioned in one of the original threads about unlimited edition E1 cards. Not exactly sure why. We know the unlimited edition Ponyta is a promo from a magazine, but how the Charizard and Pichu are released I’m not sure.
Although still extremely rare, they are slightly easier to find than the Pikachu (and most other Commons), which I’ve only seen once thus far in the collection of a fellow Pikachu collector and online friend of mine. Hopefully I’ll be able to find a copy of my own one day… (and likewise with the unlimited edition World Championship Pack Seviper and Battle Frontier, to complete my Seviper collection).
Greetz,
Quuador