Firstly i would like to state that i have no affiliation with this project, and don't know and have never spoken to the creator. I'm just some guy who enjoys this mod who wanted to try and be helpful.
So with that out of the way i will begin. In Bleach vs Naruto you select your preferred character out of either anime and beat up whoever the other guy picked. But things aren't this simple, the a.i will normally become more powerful than you and remain that way unless you make the most out of using items. The creeps around the map that you fight to level up and unlock and strengthen your abilities also drop gold. You use this gold to purchase items that make your chosen character meaner and as a result better at beating stuff up. Many items in these shops will "components" in their tool-tip, underneath components it will list items you need to craft the item. You will need the items in your inventory to craft the item once you have the components proceed to purchase the item you want and the components will disappear leaving you with your desired item giving you whatever bonus it comes with. If you purchase that item before the components the item will not have any effect on you, you can purchase the components after the main item and it will still work, the component items will disappear and you will be left with a the functioning items. Now this is something it took my a long time to figure out, you may or may not have figured it out already but i feel this will be useful for some: Some items will claim they are out of stock, to craft these items simply put the component items in your inventory, the item will then automatically use up the components and add itself to your inventory without the need to purchase it yourself.
One more thing i forgot to mention in the "components" section of many items tool-tips it will say "recipe" the recipe is the item itself before you craft it. So when you buy an item that requires components you are buying its recipe.
Alright that's all i have for you guys i hope its understandable and that it helps some of you out. Have fun playing the mod.