Spells

Original
Espers teach their original spells at their original learn rates.

Original (Random Rates) (-esrr)
Espers teach their original spells at randomly chosen learn rates using a uniform distribution.

Shuffle (-ess)
Original esper spells are randomly assigned to espers with their original learn rates using a uniform distribution. The number of spells each esper teaches is unmodified.

Shuffle (Random Rates) (-essrr)
Original esper spells are randomly assigned to espers with randomly chosen learn rates using uniform distributions. The number of spells each esper teaches is unmodified.

Random (-esr)
Esper spells and learn rates are chosen at random using a uniform distribution. The number of spells each esper teaches is randomly selected within the given range using a uniform distribution.

Random Tiered (-esrt)
Esper spells and learn rates are categorized by tier and chosen at random. Higher tier spells and learn rates are less likely to be chosen. The number of spells each esper teaches is randomly selected using a uniform distribution.
For more details: Esper Spell Tiers

Bonuses

Original
Esper bonuses are unmodified.

Shuffle (-ebs)
Original esper bonuses are randomly assigned to espers using a uniform distribution.

Random (-ebr)
Given percent of randomly selected espers have bonuses selected at random using a uniform distribution.

MP

Original
Esper MP costs are not modified.

Shuffle (-emps)
Original esper MP costs are unmodified but randomly assigned to espers.

Random Value (-emprv)
Esper MP costs set to random value within given range using a uniform distribution.

Random Percent (-emprp)
Esper MP costs set to random percent of original value within given range using a uniform distribution.

Equipable

All
All espers can be equipped by all characters.

Random
Espers are equipable by a random number of characters between 1 and 12 selected using a uniform distribution. Gogo and Umaro are excluded.

Random Unique
Espers are equipable by a single random character selected using a uniform distribution. Gogo and Umaro are excluded. Though unlikely, this option can result in some characters unable to equip any espers or a single character able to equip all espers.

Random Unique Balanced
Espers are randomly distributed among characters using a uniform distribution such that each character can equip at least 2 espers. Gogo and Umaro are excluded.

Multi-Summon (-ems)
If enabled, espers may be summoned multiple times in battle. Otherwise, espers may only be summoned once.

Natural Magic (-nm1, -nm2)
Select which character will learn natural magic.

Randomize Levels (-rnl1, -rnl2)
The levels natural spells are learned at are randomly selected between 1 and 99 using a uniform distribution.

Randomize Spells (-rns1, -rns2)
The 16 spells naturally learned are randomly selected using a uniform distribution.

Menu Indicator (-nmmi)
If enabled, the word “Natural” will appear next to MP in the status menu for characters who can learn natural magic.