General Tactics
Jiren is purpose built to control neutral. His Ki Blasts are all very good, but don't over use them only to be punished. If the opponent is zoning you, 214S is a simple and effective way to stop them. 214H is a one bar reversal against normals, but don't spam that either as it is easily punishable and you cannot make it safe if it doesn't catch anything. Once you get them to block, that's when the real fun begins. Jiren may not have a fast low, but his stagger pressure and frame traps lead to some of the highest damage in the game.
Team positioning
Point
Jiren is self sufficient enough and has a good enough assist he's better off further back in your team.
Mid
Jiren works well here. An extra assist is Handy for blockstun or combos into Dragon Rush for sliding knockdowns, and it also allows your point to use his assist.