There are two main reasons: Playability in the Pokmon TCG Cards like Ultra Ball, Countercatcher, and Pokgear 3.0 are crucial for tournament decks
Klang doesn't have an Ability but it does have two moves, the first move is called Charge Beam and for two colorless energy cards it does 20 damage, plus if you get a heads when you flip a coin, you can move an energy card from your discard pile onto Klang
However, a deck may want fewer lands alongside ramp spells if the goal is to get to 4 or 5 mana on turn 3
They harken back to the legendary birds from 2004's ex Team Rocket Returns set, though this time only Moltres gets an ex form
Ok Booster Box (Pokemon Legendary Collection) Details More Photos: Pokemon Legendary Collection: Booster Box All prices are the current market price
I always (falsely) assumed they were two of the same cards with different artworks for the a and b set numbers, like the Yellow A Alternate a numbering for the XY era