A promo card is a card where beside the symbol (RARE, UNCOMMON, OR COMMON) it says the word "Promo".

Pokemon:  Pikachu
Set: Basic
Level: 12
Card Number: 58
Pokemon Number: 25
Price: $5.00
Description:  This card is a normal basic card.  It is not holographic.  Their is also a little "E3" below the picture.  This card was first released at the 1999 "Electronic Entertainment Expo".  It was held in Los Angeles, California  (May '99).  Later, this card appeared in "Nintendo Power" magazine's September '99 issue with a much larger distribution.

Pokemon: Pikachu
Set: Jungle
Level: 14
Card Number: 60
Pokemon Number: 25
Price: $6.00
Description: This card is a normal Jungle expansion.  It is not holographic.  Their is also a little "W" below the picture.  It was first released in "The Duelist" magazine's September 1999 issue as a promotional insert.

Pokemon: Pikachu
Set: ?
Level: 16
Card Number: ?
Pokemon Number: 25
Price: 1st Edition - $35.00
          Regular     - $9.00
Description: This card is not a holographic card and it has a small star and it has a "Promo" beside it below the Picture.

The 1st Edition card was initially released in Japan as one of the two promotional insert cards in "Hyper Coro Coro" magazine's May/Spring issue.  Later, the 1st Edition version of this card appeared in randon U.S. Jungle booster packs as a mis-collated card.  Even Later, this card was released through "Wisard's of the Coast's" official Trading Card Game (TCG) Pokemon League in much larger distribution.  Most copies of this card released through the League are not 1st. Edition.

Pokemon: Jigglypuff
Set: ?
Level: 16
Card Number: ?
Pokemon Number: 39
Price: $42.00
Description: This is a non-hologrpahic card with a small "Promo" sign below the picture.  This card was initially released in Japan as one of two promotional insert cards in "Hyper Coro Coro" magazine's May/Spring issue.  To this date, this card has not yet been officially released in the U.S. but it may appear as a promotional card in the official  TCG League (and the value should drop significantly once it is in large distribution).