I remember Inoichi can talk to everyone using his ability. How did they do it? Does the devices involved in amplifying his ability? The bubble shaped and the helmet like device? Also he can use Shikaku to talk to all people during the war. Can someone explain? Thanks
Members of the Yamanaka clan have an ability called Mind-Body Transmission Technique, and during the great ninja war, Inoichi uses a variant of this to communicate with ninja on the battlefield via telepathy.
Inoichi requires a chakra transmission communication device in order to utilize the mind-body transmission technique:
While not necessary for Ino, Inoichi required the aid of a device to make use of this technique. He was also prone to overexert himself as keeping up a connection with the entire Allied Shinobi Forces for more than ten seconds caused him to suffer a nosebleed.
His first act within the war, was to set up a barrier with Ao with which the Sensor Division could use to monitor the battlefields from headquarters.
The moments we see Inoichi interacting with Shikaku are not to supplement the mind-body transmission technique, but rather to transmit Shikaku's thoughts to the ninja on the battlefield:
When headquarters needed to get in contact with Darui, Inoichi used a variant of his telepathy by placing his hand on Shikaku's forehead but told him he could not hold the connection for long. Nevertheless, this allows Shikaku himself to telepathically contact Darui, Ino, Shikamaru and Chōji, where he told them of his strategy to seal Kinkaku.