Breeder Cards are effect cards that can change the way you play an entire Battle Card match in general, rather than just a single turn.
Some of them may be of the SPE, POW or BLK type and have simpler effects, such as affecting the opponent's amount of Guts or even causing some simple Damage. But the vast majority are of a unique type called ENV (Environment) and have the continuous effect by totally altering the battle system.