Touya Todoroki or Dabi is the son of Endeavour. He is one of the most dangerous villains in the series and is extremely powerful.
Endeavor on the other hand is the strongest hero in Japan. He is extremely powerful and his power was only second to All Might.
A battle between the father and son seems inevitable as Dabi seems to hold a grudge against Endeavour. In an all-out battle, Endeavour is more inclined to win the battle.
Endeavor is the most powerful hero and has Hellflame which is his strongest attack. This attack can burn victims without a single trace and is extremely dangerous.
Dabi's flames are much hotter but he cannot use them without hurting himself. Instead of inheriting Endeavor's heat resistance Dabi inherited his mother's resistance to cold.
As it stands, Dabi cannot use his quirk without damaging his body. Due to this, he cannot fight for a long time. Also, in terms of physical strength, Endeavor is far stronger than his son.
Dabi does not have the physical strength Endeavor holds and only has his quirk which he cannot use for a sustained period without destroying himself in the process.
When it comes to an all-out battle, chances are, Endeavor would win the battle. Dabi can only win if he destroys his father early on in the battle, which is highly unlikely.