Generating Enemy Stats (GBA)

This content was originally provided by Nitrodon.

To calculate the stats for enemies who automatically Level up:

First, the class growth rate in a stat is multiplied by the number of Levels gained. Then, a RN is generated between 7/8 and 9/8 of this value (as opposed to the usual 0-99 RNs). Finally, that random number is used as the total growth rate, and a second RN is used accordingly to determine how much that stat increases. This is then repeated for every stat (except for FE7 Luck).

An enemy (at Level N) gains Levels as follows:

1. If the enemy is a promoted generic, it gains 9 Levels (Easy/Normal mode) or 19 Levels (Hard Mode, including all three FE7 Hard Modes) in its corresponding unpromoted class.
2. If the enemy is a generic, it gains N-1 Levels.
3. If it's FE6/FE8 Hard Mode or FE7 HHM, the enemy may gain some amount of Levels.
4. If it's FE6 Hard Mode on Chapter 5 or earlier, the enemy may gain some amount of Levels again. Don't ask me why.
5. If the enemy is a generic in FE8 Easy/Normal mode (I haven't checked the Japanese version), throw away all of the stats gained up to this point. The enemy gains N-3 Levels (and no promoted Levels) from the class base stats.

Level gains in different steps of this process are not combined into a single growth number. Instead, the "Level up" routine is run multiple times per enemy, using 12-14 (depending on the game) RNs each time.

The Hard Mode bonuses (steps 3 and 4) are as follows:

FE6 (offset 0x13 in the chapter data):

Chapters 1-2:    4  Levels
Chapters 3-4:    5  Levels
Chapters 5-6:    6  Levels
Chapters 7-8x:   7  Levels
Chapters 9-10:   8  Levels
Chapters 11-12x: 9  Levels
Chapters 13-14x: 10 Levels
Chapters 15-16x: 11 Levels
Chapters 17-18:  12 Levels
Chapters 19-20x: 13 Levels
Chapters 21-22:  14 Levels
Chapters 23-24:  15 Levels
Final Chapter:   16 Levels

FE7 (offset 0x14 in the chapter data):

Prologue-Chapter 10:      3 Levels (not that it matters)
Chapter 11-Final Chapter: 5 Levels

FE8: Unknown

Some miscellaneous notes:

1. FE6 Chapters 10 and 11 give different HM bonuses, which probably affects Klein and Tate.
2. If you use the cheat that sets all RNs to 0, the stat gain will be 1 more than the minimum in most cases, and exactly the minimum otherwise.
3. FE8 promoted enemies were completely nerfed in easy and normal modes. A Level 3 promoted enemy has the stats of a Level 1 enemy.
4. I haven't checked, so I don't know which routine Ephraim, Eirika, Cormag, Amelia, Duessel, Innes, and Saleh use to Level up when they appear at a higher Level. They probably either use this routine or the usual 7 RNs/Level.