Second Marienford War

They are elite warriors selected by the Admirals and Gorosei, trained to face high-level pirates.

If they are there: extremely intense hand-to-hand combat.

They would be able to hold off samurai, giants, and the Mugiwara Fleet while the Admirals attack.

They would be the ones holding up the execution, trying to get Luffy to the gallows.

The five elders do not normally fight, but their mere presence represents the ultimate authority of the World Government.

If they were to actively intervene:

They could order the Navy and the Pacifists to move strategically.

Their decisions could include invoking the world's maximum force, blocking allies, or manipulating politics to justify any atrocity.

Even his physical appearance at the execution would be a global political message, showing that Luffy is a real danger to the world order.

Akainu, Kizaru, Fujitora (or the current admirals) would appear to execute Luffy.

Each one represents a tremendous force:

Akainu: Lava, Offensive Haki, Pure Brutality.

Kizaru: speed of light, capable of destroying entire fleets in seconds.

Fujitora: gravity, environmental manipulation, and colossal attacks.

Zunesha only acts when given a direct order. The first time in centuries she heard one was from Momonosuke… but she also showed a connection with Luffy through the Voice of All Things.

If he knew of Luffy's danger, he would respond without hesitation, because he sees him as the heir to Joy Boy's Will.
(it all depends on what luffy does)

The giants of Elbaf consider Luffy an honorable warrior.

Brogy and Dorry would see the execution as an injustice and go to fight.

Giants against the Navy: one of the most feared forces in the world. (It all depends on what Luffy does.)

The fish-men feel that Luffy is the true savior of their island, the man who will fulfill the promise of peace.

Jinbe would already be there, but the rest (Neptune, Shirahoshi and the fishmen soldiers) would also move.

Even the Sea Neptunes could appear with Shirahoshi (Poseidon), changing the balance of the battle.
(it all depends on what luffy does)

Dragon, Luffy's father, would never allow his son to be executed.

It would be the perfect excuse for revolutionaries to declare open war on the World Government.

Ivankov, Sabo, and the entire revolutionary army would arrive, turning the rescue into a global revolution. (It all depends on what Luffy does.)

Law wouldn't let him die: he feels his alliance with Luffy goes beyond a deal. He'd join his entire crew in battle.

Kid, though more proud, would see that losing Luffy would mean letting the Navy crush the age of pirates. He would also join, out of conviction and pride.

It would be a "Supernova Reunion", showing that the new generation will not let their future be taken away (it all depends on what Luffy does)

Obviously, the prime crew would be the first to launch.

Zoro, Sanji, Jinbe, Franky and the others would accept nothing less than breaking the gallows and rescuing him.

This time, they would be much stronger than in Enies Lobby, where they had already declared war on the Government for Robin.

They'd be willing to sink Marineford 2.0 for Luffy. (It all depends on what Luffy does.)

The pirate empress would react immediately.

Hancock is in love with Luffy and would do anything to save him.

He would summon the Kuja and launch a frontal attack on the Navy.

His Haki and petrification abilities would be devastating weapons in chaos. (It all depends on what Luffy does.)

As a grandfather, Garp would never allow Luffy to be executed.

But as a Marine, he would have to betray his duty.

Vivi and the entire town would rise up.

Luffy saved Alabasta from Crocodile, and the kingdom never forgot him.

Vivi would use her influence as a princess to move international contacts against the World Government.

Kohza and the rebels would lead forces, proclaiming that Alabasta would never allow their savior to die like that. (It all depends on what Luffy does.)

Zou's mink warriors (Inuarashi, Nekomamushi and the entire tribe) would enter Sulong mode under the moon.

They would remember that Luffy defended them and fought alongside them against Kaido.

Their combat force would be brutal: hundreds of transformed minks rampaging through marines.

Inuarashi and Nekomamushi would lead like they did on Onigashima, roaring that Luffy is their ally for life. (It all depends on what Luffy does.)

The Wano samurai, led by Momonosuke and the Red Scabbards, would not hesitate to set sail.

Momonosuke sees Luffy as his savior and older brother, he would not allow the man who liberated his country to be killed.

Yamato would go to the front, with all the fury of his “Nika-admiration”, launching himself directly against the Navy.

It would be an army of samurai willing to die rather than let their "Great Captain" fall. (It all depends on what Luffy does.)

Shanks considers Luffy his spiritual heir, the boy to whom he entrusted his hat and in whom he placed his dream.

If he knew, he wouldn't stand idly by. Just as he stopped the Marineford war when Ace died, he would act immediately.

You could see this situation as the moment to fulfill your promise: to protect Luffy's dream until he becomes a great pirate. The Red Hair Pirates are one of the most balanced and feared crews in the world.

Shanks could arrive at the execution site, just like he did at Marineford, and stop the conflict with his mere presence thanks to his reputation and King's Haki.

I would directly confront the Navy and demand Luffy's release (it all depends on what Luffy does)

The 7 captains and their crews would rush to the rescue without hesitation, even if it was a suicidal move, because they all swore loyalty to Luffy and see him as a leader worthy of following.

The attack would be chaotic but devastating, with each captain using their skills and armies to break through the Navy lines.
Bartolomeo (Barto Club):

He would erect massive barriers to protect Luffy from the cannons, the Admirals, and the Vice Admirals.

It would act as a “human wall” around the execution platform.

Cavendish (Beautiful Pirates):

In his Hakuba mode he would tear through the marines at high speed, creating chaos in the ranks.

Their goal would be to pave the way for Luffy.
Don Sai (Happou Army):

With his martial arts techniques enhanced by Haki, he would collapse the ground and launch area attacks.

His 1000 men would be an offensive wall.
Ideo (Fighters Alliance):

I would go straight for the strongest enemies in close combat.

His small but powerful team would act as a shock force.
Leo (Tontattas):

The Tontatta would use their speed and stitching to stealthily free Luffy.

They would sabotage weapons and shackles.
Hajrudin (Pirate Giants):

As a giant, it would attack the Navy's towers, ships, and cannons, destroying its infrastructure.

He could charge at the Pacifists or even confront Vice Admirals.
Orlumbus (Yonta Maria Grand Fleet):

He would mobilize his army of 4,300 men and dozens of ships to block the naval fleet.

It would be the strategic and logistical support of the battle
(it all depends on Aga Luffy)