Infinite Stats & Unlockables.
Infinite stats for Avatar Logbook characters.
If you collect a large number of stat increasing items and gold, then save the game. Then recruit a character from the Avatar Logbook, and apply as many stat increases as desired to them. Now, update the avatar logbook for that character. Create a new saved game. Load the first saved game, then repeat the process.
Successfully complete Lunatic mode to unlock Lunatic+ mode.
You must successfully complete the game to unlock the "Support Log", "Theater", and "Unit Gallery/Sound Test" options in the Extras menu.