Kumite gata are series of techniques that can be seen as Kata ohyo: applications of Kata techniques. These Kata are known under several names such as: Kumite gata, Ura waza, Kumite no Ura and for example Kata Ohyo.
Ishikawa sensei new lots of "Ura waza" but did not structure them. Sakagami sensei uses numbers for his Kumite gata within his Aiwakai. Eventually it is of course the technique and execution that matters and not knowing the number or a name, but it does help to memorise when you start to learn it.
In contrast to Kihon Kumite, you deal with Ukemi's attack by counter attacking right away. In Kihon Kumite you counter in the second or even third movement. It can therefore be concluded, that, even though they are not actual fighting techniques and are not designed as such, Kumite Gata are series of techniques that have more focus on overcoming the opponent and controlling him. The techniques are more towards application as opposed to Kihon Kumite. Of course, neither Kihon Kumite nor Kumite Gata or ready-to-use techniques, but clearly there is a different emphasis.
Kumite gata are originally a series of 36 techniques. The number 36 is not a coincidence, but is the result of the following sum: 2 x 3 x 2 x 3 = 36
The first two of the order that I chose are Ai gamae and Gyaku gamae, which deals with the initial position. Then, the attack can be classified as Gedan, Chudan and Jodan and thereafter follows the choice of moving to the inside or outside of the opponent which is called Uchi zeme and Soto zeme. Finally there are different moments that you can use to move. These are Go no sen (react on), Sen no sen (interrupt) and Sen sen no sen (act before). The explanations of "react on", "interrupt" and "act before", are pretty short and shallow, but should give an impression of the different kinds of timing. We will share a link here is there if the blog of the Three types of Sen is online.
Like Kihon Kumite, Kumite gata starts from Hanmi chudan gamae.
Literally half body, which means that your hip has to point diagonally to the side (say 45 degrees).
Chudan refers to the middle section of your body. This is the part of the body between your hipbone and the base of your collar bone.
Kamae can be translated as posture. Formally you should write chudan gamae, because the word is preceeded by another word that is part of it, in this case chudan. This has to do with rules of grammer and pronounciation.
The first movement is equal to the second movement of Kihon Kumite #1, with the exception of jodan uke instead of chudan uke (Check the banner of this page to see Sakagami sensei's execution in close-up). The right shoulder has to be pulled little more (or at least that feeling) compared to chudan uke. Connect the three movements and let them use each other positively.
The second punch for example, can be made powerful by using the shoulder that was in a way prepared during the first movement. The second punch has to be delivered before Ukemi can recover from the first punch as you jam the front leg to prevent a kick with the front leg or at least make that more difficult to do.