One of the most unique things about Breath of the Wild is the fact that players can force Link to face off against Ganon as soon as they have received the Glider from King Daphnes, although this isn't a great idea considering how little hearts and stamina he will have. It is recommended that players complete at least some of the Divine Beasts beforehand, but not doing so will result in a very different boss battle in Hyrule Castle.
Any Blight bosses that haven't been beaten before facing off against Calamity Ganon will fight alongside him, turning a one-on-one into a boss rush that can be one of the most satisfying and challenging battles in the game. It shouldn't be attempted without some prior planning, however, as fighting these bosses back to back can test even the greatest hero's resolve.
10 Equip Good Armor
It should be a no-brainer, but Link should be wearing something other than the ragged clothes he wakes up in when he confronts Ganon. If players are wanting to fight the boss rush version of this battle, the Ancient Armor set is a good choice, although it can be difficult to obtain, as well as the Barbarian, Phantom, and Fierce Deity armor sets for their attack bonuses.
The standard Hylian uniform or Champion's Tunic can be used, but not having an inherent attack buff or advantage against machines will make this battle stretch out in time, particularly if players are attempting this battle in Master Mode.
9 Upgrade Armor
As well as getting Link's hands on some good armor, it should be upgraded for maximum defensive capabilities as well. The bosses may be fairly easy to defeat if players already know how to do so, but that doesn't mean Link shouldn't be prepared to take a heavy hit if something goes wrong.
Although fully upgrading isn't necessary, it should be done at least twice to gain the set bonus some armor sets have when wearing all three pieces of the same set.
8 Master Perfect Block and Dodge
This is something that should be done regardless of whether or not players are attempting the final boss rush, but mastering the block and dodge mechanics will save Link a world of hurt in the long run. Aside from saving him from taking some heavy hits from the Blights and Ganon, they open them up to take Flurry Rushes and other heavy hits if executed correctly.
As Calamity Ganon likes to fire Guardian lasers at Link, master this aspect of blocking to deflect lasers is also recommended, as Ancient Shields aren't always going to stick around to do the work for Link, particularly if players need to make an untimely block to prevent death.
7 Complete As Many Shrines As Possible
Since Link only starts the game with three hearts and one wheel of stamina, completing as many shrines as possible should be done before the final battle, whether or not players are attempting the boss rush.
As some shrines are locked until certain Divine Beasts are defeated, players won't be able to complete all of them no matter how hard they try if they want to go for the full boss rush. Luckily, there's more than enough shines in spite of this to make sure Link has a decent amount of hearts and stamina going into the final fight, though this does mean that Link won't be able to wear the Hero's Clothes rewarded for completing all 120 shrines.
6 Upgrade The Sheika Slate Runes
Like learning how to dodge and block, upgrading the Sheika Slate Runes should be done regardless of whether or not players are attempting the boss rush. Although three of them can be upgraded - Bombs, Stasis, and Camera - only Stasis is really useful in the final battle.
Fireblight Ganon is the only boss that requires Bombs and they don't need to be used frequently enough to need Bomb+, while the Camera is utterly useless in battle. Stasis+ is really needed against the most annoying Blight, Thunderblight Ganon, but can be useful against all of the bosses in certain situations.
5 Learn To Cook
Before going into Hyrule Castle, players should cook up a storm and make sure they have enough Meat Skewers and potions to take on multiple bosses one after another, as well as the regular monsters that lurk within.
If Link isn't wearing armor with a secondary effect, players should make sure they have potions and food that give bonuses to attack, defense, and elemental resistance, while also making sure they have a decent supply of food that can restore hearts in a pinch.
4 Bottle Up Some Fairies
As players may not have acquired Mipha's Grace before confronting Ganon, stocking up on a bunch of fairies is probably a good idea. Even though the classic empty bottles of past Zelda titles are long gone, fairies can still be collected by Link if players are fast and sneaky enough to grab them before they fly away.
Fairies can be found anywhere there is grass or bushes that can be cut down, but they appear randomly and it is more likely players will find insects instead. The most efficient way to find fairies is at Fairy Fountains, where there will be a handful surrounding the main structure as Link approaches, though they will fly away if he isn't sneaky.
3 Stock Up On Ancient Arrows
Robbie may be a little strange, but he's at least useful in terms of what he can provide for Link. As they aren't regular monsters, the enemies in the boss rush won't be instantly killed by Ancient Arrows, though they will take significantly more damage than they would by regular arrows.
They can be difficult to obtain early on, but there are several areas in Hyrule that are littered with dead Guardians that will provide the materials needed so Link can buy a decent amount from Robbie's machine.
2 Grab The Hylian Shield
Hiding within the castle walls is the best shield Link can equip, the Hylian Shield. Aside from having a ridiculous 90 defense, it has a durability of 800, far higher than any other shield in the game by a wide margin.
Players will have to navigate the labyrinthian castle and defeat a Stalnox mini-boss for it to appear, but if they have adequately prepared themselves before entering Hyrule Castle, this shouldn't be a hard battle.
1 Get The Master Sword
There's no reason to not use the Master Sword in Hyrule Castle, as this is one of the few places in the game where it won't lose charge when using it on regular enemies.
It also has the bonus of dealing heavy damage to all of the Blights and Ganon, which can shave some crucial seconds off of the battle if attempting the boss rush in Master Mode.