Well I think alot of the unit's we know about were formed later on after the Battle.
Remember when the war began the Kamino's had a lay out of what the army was going to be.Clone's were bred for the various postions rather then being selected for their potential and integrity.Any clone that showed a "defect"such as independcy usually dissapeared.I think alot of the Battlions and Corp's came in to being due in part to Alpha-17's training regimen which for the first time actually encouraged the clones to show their unique qualities,clone's started customizing their equipment and units and that I think is when many corp and Battlion names began to pop up
Several Republic Commando units were dropped in(Though they did not participate directly in the battle)
Delta Squad,Theta Squad,Lambda Squad,Teroch Squad
And if Stomper hasn't seen this squad already
Omega Squad
http://starwars.wikia.com/wiki/Omega_Squad(though they were formed after Geonosis)
