How to transfer photos from iPhone to other mobiles via bluetooth?

You can't. The iPhone does not support the relevant bluetooth profile to allow this (in fact it only supports use with a headset)

Transfer Photos from iPhone to iPhone

I think using bluetooth to transfer photos between iPhone is slower that using FonePaw iOS Transfer.
FonePaw iOS Transfer can copy photos from iPhone to iPhone without any restrictions. This software supports all iPhone models, including iPhone 6 and iPhone 3GS and it supports transferring photos from your iPhone to another iPhone with different Apple ID.