Tengen only has 1 losing matchup in the series and it's vs CSM users as they can be manipulated since they are closer to a curse than a human(Takaba also negs but doesn't apply here)

Yuta and Yuki wonder why Tengen even needs to be guarded because of their immortality, Tengen gives them a breakdown as to what Kenjaku is planning then drops the bomb on them that he is susceptible to CSM.  It doesn't apply to these 4 though.

Jogo asks who is stronger, Gojo or Tengen, and Kenjaku replies and tells Jogo it isn't anti-aging immortality, but just immortality(Can't die), but reassures him that they don't have to worry about Tengen because they don't actively interfere with the world(he could though)

This is further supported that Kenjaku never attacked Tengen themself during the fight with Yuki and Choso despite Tengen giving active support, as nothing Kenjaku would do would do anything except his CSM

Tengen evolved soul exists everywhere and Tengen doesn't really have a true body if they don't want to.  Tengen is ABOVE any sorceror, they are an evolved being. Even if they attack the body Kenjaku approached after the fight, they wouldn't be able to kill Tengen anyways. Tengen could simply remove their form and consciousness and be present everywhere with their soul.

Sunyata barriers can suppress black hole level attacks, and only Kenjaku who is 2nd best in barriers was able to breach inside Tengens area.  Tengen can dismantle the 2nd best barrier users domain if it was closed within 10 seconds, even when surprised by open domain can still quickly dismantle it

Tengen can hide within empty barriers, could use various techniques to block any of them out(Gojo was able to be stalled by much weaker barrier users), though they wouldn't need to since none of them could kill them.

Tengen has infinite CE reserves or perfect efficiency since they have maintained barriers as complex as theirs for decades while also keeping a physical form via barrier techniques with no sign of CE drain at all.

TLDR Tengen negs they have no wincons

Tengen> Gojo, Sukuna, Dabura, Modulo Yuji in 1v4