[WHAT IF] Odin was there during the final battle in Endgame?

If Odin was present in the final battle in Endgame, then Thanos would have had no chance in winning against the Avengers and the battle would have ended very quickly without any casualties like Iron man.To explain why, let me explain to you what would happen if Odin was alive and well during infinity War.

The whole reason why infinity war even occured at the time that it did, was due to the fact that Odin just died, and Asgard was destroyed. Thanos feared Odin and he knew that when Odin was alive, he could never achieve his goal of eliminating half of all life in the universe. Thanos is very old and maybe even centuries old; he is older than what everybody thinks. Remember, he didn’t start collecting infinity stones until immediately after Thor Ragnarok, where Odin died and Asgard blew up. He waited for the right moment to strike. Remember, there was almost nobody to protect the universe at that time. Asgard had fallen, Ego was dead (Ego too may interfere with his plans, but his son, Peter Quill took care of him), The Ancient One was dead too, so, there were almost nobody that was a direct threat to him.

Even if he tried to stay under Odin’s radar, then it would still be near impossible to get the space stone as it was safely guarded in Asgard, he couldn’t go for the reality stone as due to the fact that it was given to the collector in Knowhere, they must have kept close tabs on it. He even couldn’t have gotten an infinity gauntlet from Eitri the dwarf if Odin was alive, because as he said, asgard was supposed to protect it. Whatever stone he goes for, Odin will notice. He was helpless if Odin stayed alive.

Now let’s think for a moment that Smart Hulk also revived Odin using the infinity stones in Endgame. Then Odin would arrive to fight off Thanos on Earth. Then Thanos wouldn’t stand a chance and the Avengers would have won without any unfortunate casualties.

In short. If Odin participated in any time during Infinity War or Endgame, then Thanos would be dead. But if somehow Thanos managed to obtain a few infinity stones like time, power, soul, reality or mind (space is impossible to collect as it is the most heavily guarded one), then even Odin will find it difficult to stop him and in such a scenario, Thanos may succeed after all.

Hope that answers your question!