I used MT Manager to edit classes.dex>age.of.civilizations2.jakowski.lukasz>Menu_CreateNewGame_Options_v2
Find the first line with the word AI_AGGRESSIVENESS in it
The two lines above it will be
const/16 v16, 0x32 (0x32 is the min ai aggressiveness written in hexadecimal)
const/16 v17, 0x190 (0x190 is the max ai aggressiveness written in hexadecimal)
Change 0x32 to 0x0
Edit: A little clarification. This wasn't discovered by me. @Dmitry Bunt told me how to do this.