MonkeyLord nailed it.

Even with the future breakthrough/skill trial of Tendo Pain, his weaknesses in PvP were not addressed (as a front man.) You could possibly use him as a support with his improved chases, but there are much more practical ninjas out there.

Like MonkeyLord said, he's great for the few challenges in the game where you need to clear a field of enemies that aren't particularly threatening. He is easily buffed (note that teammates c*e Rinnegan buffs.) Even Edo Hiruzen is generally a slower tactic than pain nuking due to limited targets hit.

Fun fact, before they nerfed Tendo Pain he was never really *l-star anyhow. He used to have a prompt mystery and the old meta supported the "turn 2 mystery" type battle, but as a "super rare" he was heavily outshined by his counter part in the treasure, the hit-or-miss Hashirama barrier.