Techniques in Kanku-sho that also appear, unchanged, in Kanku-dai
1) Gedan-gamae, taken out of its sequence in isolation, appears twice in both kata and is performed slowly in both.
2) Yoko-keage, yoko-uraken, mae-empi-uchi, appears in both kata just before the final main sequence.
3) Kosa dachi, uraken, uchi-uke, nihon zuki, appears twice in the main sequence of Kanku-sho, and once in the altered final main sequence of Kanku-dai.
Techniques and sequences that have a counterpart in Kanku-dai
1) What I call the 'main sequence' in both kata are analogous. In Kanku-dai it consists of jodan shuto-uke, mae-geri, turn into manji-uke, nagashi-uke, gedan nukite and then it ends with gedan gamae. In Kanku-sho it consists of kake-dori, mae-geri, uraken, uchi-uke, nihon zuki, turn into kasui-ken, and end with gedan gamae.
In both kata the sequence is performed in the same way - first to the south (I'm calling north the direction you face when you start the kata), then to the north, and then to the south again, and in both cases the third sequence is altered at the end.
Both contain an opening move and a front kick. Both turn into a technique that is related - manji-uke in dai, kasui-ken in sho, and both end in gedan gamae done slowly.
In Kanku-dai the changed main sequence becomes the end of the Kanku-sho sequence (uraken, uchi-uke, nihon zuki). Both changed main sequences then turn into the move that leads to ryote-fuse.
2) Ryote-fuse. In Kanku-dai a jodan ura-zuki is executed before a drop straight down into ryote-fuse (both hands on the ground), then you turn into gedan shuto-uke in a low stance. In Kanku-sho you jump into a mikazuki-geri and drop into ryote-fuse with an ushiro-geri (sometimes executed in mid-air, sometimes upon landing). You then perform a rapid switch-step into the low-stance gedan shuto-uke.
3) The final four techniques of Kanku-sho (turn west into uchi-uke, oi-zuki, repeat to the east) have something of a counterpart in Kanku-dai's turn west into uchi-uke, gyaku-zuki, repeat to the east with nihon zuki.
Techniques in Kanku-sho that relate to other kata (not Kanku-dai)
1) Manji-uke, shift into kiba-dachi, morote-zuki, has some correlation with Jion's sequence - the same but kagi-zuki instead of morote-zuki.
2) The spin-jump into kokutsu-dachi, shuto-uke also appears in Empi, and also after a shifting move forward. As the kata have very different origins one can assume this characteristic Shotokanisation came from the same person, most likely the dynamic Yoshitaka Funakoshi.
3) The jo-uke can be seen in Bassai-sho, another Itosu creation, though it does not have the follow-up otoshi move seen in Kanku-sho. It does appear twice with otoshi in the kata Meikyo, though the otoshi thrust is done in zenkutsu rather than kokutsu-dachi.
4) The kake-dori is similar, though not quite the same, as Bassai-dai and sho's kaeshi-dori. Kanku-sho's kake-dori is followed up with a mae-geri, whereas the Bassai grasp is followed up with a gedan yoko-geri.
5) The haishu-uke and then jump into mikazuki-geri, ushiro-geri, ryote-fuse, has a strong counterpart in Unsu. In Unsu, however, the haishu-uke is to the front, giving a full 360 degree technique. The spin is also 360 degrees in Kanku-sho, but the haishu is to the rear, so it is possibly slightly easier.
6) I have not really included techniques that are also seen in the Heians or Tekkis, but these would include morote uchi-uke (nidan, sandan, yondan, godan), a run of three oi-zukis (shodan), mae-geri into uraken (yondan), manji-uke (godan), morote-zuki (Tekki shodan), shuto-uke (shodan, nidan, yondan), and yoko-keage, empi-uchi (yondan).
Techniques that are unique to Kanku-sho (within the best of my knowledge)
1) Morote uchi-uke appears in a number of the Heian kata, but coupled with the backwards slide, it becomes a characteristic technique of Kanku-sho.
2) The follow-up tsukis and sharp pull-backs (hineri-kaeshi) don't appear in another Shotokan kata, as far as I know.
3) The kasui-ken, though related to manji-uke, appears only in Kanku-sho.