This is how I picture the fight would happen:
Hashirama: infinite darkness Justu
Jiraiya: giant swamp of the underworld and reverse summon himself and Orochimaru into toad mouth trap.
-Hashirama releases infinite darkness Justu
Hashirama: Deep forest emergence(to raise them from the swamp)
-both Hokage's look into the distance watching a massive toad flame bomb coming towards them.
Tobirama: giant waterwall
-but collaboration fire attack overpowers even Tobirama's water style
-Hokage's jump out of the way just in time
Orochimaru uses the extended Kusanagi sword and tries to hit Hashirama
-Hashirama tries to block with wood but his wood isn't strong enough to defend against Kusanagi's diamond blade.
-Kusanagi's pierces the wood and hits Hashirama, but it's a wood clone.
-but Kusanagi's burst's into a plethora of snakes chasing Hashirama, but they are immediately cut down by Tobirama's Thunder god sword.
-Orochimaru: ten thousand snakes and hurls the attack toward the Hokage's.
-Hashirama: forest of Flowering trees to collide with the snakes and use the pollen to kill any surviving snakes.
-Jiraiya jumps over the forest with Gamabunta and uses toad flame bombs to burn the forest down.
Tobirama's attacks Jiraiya with a water dragon but Gamabunta blocks the attack with his palm and gets knocked back.
Orochimaru bursts himself from underground in snake form shooting towards Tobirama and swallows him.
A giant toad tongue shoots from within Jiraiya's swamp and grabs Hashirama's ankle and pulls him under.
In conclusion, Tobirama is in Orochimaru's custody. Hashirama is inside Jiraiya's toad gourd prison.
