So I was theory crafting what the max amount of upgrades I could get for Zangetsu in the final chapter when I found an exploit that could be used to get all of them, so I figured I would list down what items you could get with and without the exploit.

The exploit in question, if you have Gebel on stage 7, enter the stage, then exit game and reload it, Gebel will continue to be in your party, even though you haven't beaten the stage. With Gebel and Ultimate Zangetsu in the party, you can access all but 1 of the items in the game. Then, before you go to the moon, head back to stage 7 and immediately leave the stage with the stage select option, and he will no longer be in your party. The only item you can't get with Ultimate Zangetsu and Gebel is the heart container in stage 5, which requires Alfred freeze the lava to reach it.

Small note: For those who don't know, Ultimate Zangetsu can do a charge attack that can break all the walls and floors that previously only Hachi could break.

With that out of the way, here is a list of the best possible character combination you could get for maximum items without the exploit. Another small note: in all stages but 5, Gebel can let you access both items, but is best saved for stage 6 or 7, so that you can get the Attack or Defense up.

Stage 1: Robert. You can break the floor on the first screen with Zangetsu to get on the path towards a magic urn. When you get to the gap you need to cross, a double jump followed by Robert's drake cannon will let you clear it. Same for the following gap after you break the wall to the magic urn.

Stage 2: Dominique. You don't technically need her in this stage for the item, but I find stage 2's boss to be one of the harder ones, so I find it is better to have a different stage that has no companion.

Stage 3: No One. I find stage 3's boss to be the easiest boss in the game, so this is the one I want to beat. You can get the magic urn by breaking the floor on the left of screen 3 with Zangetsu, and following that route,

Stage 4: Miriam. You can break the block leading to the heart container with Zangetsu, but you need someone to crawl, slide, or fly through a small hole, and since we've used Robert already, and Gebel is for later, Miriam is the best choice for this stage. With her, you can get both items in this stage.

Stage 5: Alfred. Being the only character that can freeze the lava, he is the only character that can let you reach the Heart Container on the bottom route. Bonus points, you only have to play this level once, take the bottom route through the lava to get the heart container, and in the room just before the boss, head up the stairs to grab an easy magic urn.

Stage 6: Hachi/Gebel. This is where you make your choice. would you rather have an attack upgrade or a defense upgrade? If you want attack, you need Gebel in this stage, if you want defense, you need Gebel in stage 7. I find that I kind of suck at this game, so I prefer to grab the defense upgrade to tank more damage, and took Hachi in this level.

Stage 7: Gebel/Hachi. Another stage you only have to play once. First, head up the stairs 2 screens to grab the magic urn, then head back down and take the Gebel only route towards the defense up. The spiky armored enemy that is blocking the stairs to the armor can be destroyed with a Zangetsu's charge attack.

To sum up, you can get a total of 6 magic urns, 3 heart containers, and 1 attack or defense up, a total of 10 items, with the proper character placement (which will probably take you dozens of rerolls.) By using the exploit (Gebel on stage 7, and Alfred on stage 5) you net yourself 2 more magic urns (stages 1 & 2), 1 more heart container (stage 3), and the other attack or defense up (stage 6 or 7)