3.P Tiered Gestalt Rules+What are some examples of options that change a class's tier?

Most tier 1 and tier 2 classes have the potential for the same level of power, but tier 1 classes are more versatile.  Usually, this comes down to the differences between prepared and spontaneous casters.  If an archetype or other option would turn a spontaneous caster in a prepared caster, that might be sufficient to increase the effective tier (and associated CP pricing) by 1.  Similarly, if an archetype would change a prepared caster into a spontaneous caster, that would decrease the effective tier by 1.  Some exceptions are noted in the tier listings.  Access to powerful items can also change the effective tier of a class, such as Knowstones or Mnemonic Vestments.

Martial initiators might be considered tier 3 if not for their access to supernatural disciplines.  These disciplines are stronger than their extraordinary counterparts, and so tend to increase the tier of initiators with access to them.  A single such discipline might increase a class to tier 2.5, while two or more supernatural disciplines allows them to compete with tier 2 classes in combat.  The tier listings reflect how many supernatural disciplines an initiator class has access to by default.

Some options give characters more actions per round (see Font of Inspiration for Factotums), greatly increase a character's versatility (see Psychic Reformation for manifesters), or significantly increase a key statistic (see the Many-fanged dagger for sneak attackers).  Generally, if an option doubles the power or versatility of a class, it warrants an effective tier increase.

Notably, tier evaluations are made in a vacuum - I consider how strong an option would be in a non-gestalt game.  So specific interactions between classes in a build are not considered.  Also, tier changes are not applied retroactively, so if you choose an option that increases a class's effective tier, the level at which you chose that option is the first level for which you apply the new CP price.