I hear certain flags have special effects when enabled with SkillSys. Which flags do what? Which are safe for me to use?
Global Flag 0xEE disables pop-up damage numbers in battle animations.
Global Flag 0xEF enables Fixed Growths Mode, which removes randomness from player leveling.
While not included in all versions of Builder’s default SkillSys, one version of the Casual Mode patch uses Global Flag 0xB0 to enable Casual Mode, and I hear the GitHub version of SkillSys bundles this in.
Also not a SkillSys function, but there is a patch that uses Temporary Flag 0x27 to make green units hostile to the player, so if you’re considering wanting that functionality in your hack, avoid Temporary Flag 0x27 as well.
A vanilla function: turning on flag 0x84 will hide all icons on map sprites, such as boss icons, status effects, health bars with the HP bars patch, and so on.
Aside from that, any flag named “Global Flag XX” is unused in vanilla, any flag labeled “Temporary Flag XX” has no special effects in vanilla, and I can’t remember any other major patch conflicts – but of course, make sure to check patch descriptions.
For a more in-depth glossary of all vanilla flags, see here: [FE8] EID/Flag/Event ID Glossary