Summary is here: http://www.d20srd.org/srd/variant/classes/gestaltCharacters.htm (http://www.d20srd.org/srd/variant/classes/gestaltCharacters.htm)
- You may choose to gestalt up to three levels of your choosing.
- One of those classes chosen to be gestalted must be applied to all gestalt levels. The second class pick can change. Eg: 1st level: Rogue / Fighter, 2nd level: Rogue / Wizard, 3rd level: Rogue /Cleric, is a valid gestalt combination.
- Gestalting applies only to Pathfinder classes. Please work with a DM if you attempt to gestalt any of the following: a 3.5 class, homebrew class, monster race. We may allow limited gestalt levels for those classes.
- You may not gestalt Prestige Classes.
- Gestalt levels must be consecutive.
- You may gestalt into a class combination that you'v already taken a level in.
- Gestalt classes are treated as a separate class, but class abilities can stack. This means you can't choose a favored class of Fighter, and get the favored bonus for a Fighter / Wizard. However, If you take Fighter / Wizard 3 levels, the fourth level in fighter, will still get you any 4th level fighter abilities, and unlocks 4th level fighter feats.
Additions to this.
Gestalt classing must be only for the first 3 levels. Any pathfinder class will work. Anything homebrew will need to be reviewed before gestalting is possible.
Also apply similar rules if you choose to gestalt two classes with familiars/animal companions/spirit animals/etc. Combining the familiar/companion abilities into one. Though if you choose to have two, that works as well.
Forgot to mention this but also:
-Gestalt classes are treated as a separate class, but class abilities can stack. This means you can't choose a favored class of Fighter, and get the favored bonus for a Fighter / Wizard. However, If you take Fighter / Wizard 3 levels, the fourth level in fighter, will still get you any 4th level fighter abilities, and unlocks 4th level fighter feats.