Okay, I am not sure whether the recommendation (not a hard rule, if I recall correctly) of not allowing theurge classes in gestalt actually affects gish classes, but for the purposes of this thread, I will assume gish classes are allowed.
Due to a certain thread at the WotC's forum and my recent obsession of gestalt/high level gaming caused by the horrendous lack of roleplaying here in my new home country I got inspired this morning. This inspiration lead me to dabble with the possibility of making an Iajitsu Master for the heck of it. This goes for no particular purpose apart from me killing some time and reducing my RP-deficiency. For the sake of the argument, assume all D&D 3.5 and unupdated 3.0 allowed and use 32 point buy.
So this is what I was thinking:
Venerable Dragonwrought Loredrake Desert Kobold
STR 10-4 6
DEX 11+2+6 18
CON 14+6 20
INT 13+3+6 22
WIS 9+3-2 10
CHA 17+3+5+5+6 36
I believe that leaves two points to be distributed wherever you want. It includes +6 enchantment to dexterity, constitution, intelligence and charisma as well as level ups for charisma and +5 inherent bonus to it.
Then to the class levels:
Fighter 1/Factotum 2/Cloistered Cleric 1/Feat Rogue 1/Sorcerer 1/Iajitsu Master 5/Factotum 1/Swordsage 2/Feat Rogue 1/Sorcerer 3/Swordsage 2//Sorcerer 5/Swiftblade 1/Sorcerer 5/Swiftblade 9.
This assumes flaws. At first level go ahead, pick Dodge, Mobility and Dragonwrought at first level. Proceed to get Draconic reservoir at level three. Cloistered Cleric gives Travel devotion, Knowledge devotion and Improved initiative, Iajitsu Master hands out Skill focus (Iajitsu focus). Make sure to use the Feat Rogue and Fighter level to get Quick draw and Weapon focus (katana).
Feat choices would be something along these lines:
-Compulsory: Dragonwrought (level 1), Dodge (flaw), Mobility (flaw), Improved initiative (Time domain), Weapon focus (katana) (Feat Rogue), Quick draw (Fighter), Draconic reservoir and Greater rite of passage. This means the build still has its feats from levels 9, 12, 15 and 18, Travel devotion and Knowledge devotion from Cloistered Cleric and one more from Feat Rogue. Depending on the BAB you want, you might want to start of with Factotum to fill in the skill point prerequisites.
From this point on I would personally use Swordsage's Assassin's stance for Craven and, well, Shadow blade. Use feycraft katanas to get the benefits of Weapon finesse, sunblades come awfully handy here. Divine might doesn't hurt either. Monk's belt+Ascetic mage for those who still feel insecure and Carmendine monk to mix that Swordsage AC bonus to be intelligence based.
So, eventually, you would have charisma score to initiative twice (from Iajitsu Master and Swiftblade), your Iajitsu focus dice (that is to say, 9 times your charisma modifier to damage, more with Divine might) as well as armour class thanks to Ascetic mage. Intelligence modifier applies twice to AC and once to initiative. Dexterity modifier to initiative, damage and attack bonus.
Assume you Shapechange into a gloom. Your dexterity is now 55. Your damage is: base katana damage+9d6+9x13+2d6+20+22+11. This includes STR bonus, Iajitsu damage dice, SA dice, charisma modifier for all Iajitsu dice and dexterity modifier. I trust the build to get plenty of those dice, since the initiative is through the roof.
Okay, sorry, I wrote this in utmost hurry, so there must be errors. I will be back in a bit more than an hour or so. Meanwhile, please comment and improve.