Besides pure breeds, such as Pixie/Pixie, and combinations of breeds, such as Pixie/Monol, there are Special varieties of breeds in MRA2. In previous Monster Rancher games, those have been called Pixie/????. However, for MRA2, they are designated as Pixie/SP. [I am using Pixie as an example to illustrate; every breed has /SP types.]

There are 3 different types of special breeds in the game:

[1] Sp-U These are monsters that require a storyline to be completed to unlock. The storyline may require a certain battle be fought, or a certain item be gained and used in combining. Unlocking these usually only unlocks that monster (see Legends)

[2] Sp-O the "O" stands for Open. These monsters can be obtained as soon as the breed is unlocked and you have the password to generate it from the shrine.

[3] Sp-L The "L" stands for Legendary. Knowing the password alone is not enough to generate this monster from the shrine. It can be battles that have to be won, an event that has to be experienced, or a mammoth breeding project. Completing the task will usually open several specials, but some Legends can be stubborn. Instructions for the breeds that have legends (not all of them do) are in Shrine Topics.

The designation of which SP monsters for which breeds are U, O, and L are contained in the passwords list.