@Vanessa28
For the giant bosses, I think farming the giant boss levels in the beast Ganon mode is a decent way to farm the boss materials. I'm not sure if this is in the 3DS port of the game though. It's also a decent way to earn rupees until you unlock some of the skulltula maps. I've not unlocked any skulltula maps in the Switch port yet.
Personally I find farming the gold materials from the enemy heroes to be much more time consuming. Of cause the stages that have the dividing enemy heroes are good for this, as are the Twilight Princess stages because the TP map gives double materials. Not sure if any other map area does this.
The armour badges though are not as good for many of the harder stages though. They are worthless on all stages without a favoured element. It just so happens many of the harder stages have no favoured element. Still for every other stage the badges are quite useful and totally worth going for. The Switch port actually makes this a mot more managable. The Adventure maps now have an overall difficulty. So you don't have to grind them all up at once.
The easy maps can be done with no armour badges or just the bronze ones.
The medium maps could be done with the bronze armour badges but getting silver might help a little too.
The hard maps I think need the gold armour badges. But by then you've gone through a good portion of 4x adventure maps. That's a lot of stages to find the gold materials you need. And by then farming what you need still shouldn't take too long I guess.
Overall though with a little skill the need for the gold armour badges is lessened a little on the Switch port. The reasons for this are the difficulty scaling of the adventure maps is so much better and the move to A Rank needing a percentage of life lost, not a number (which is mostly equivelant to 4 ot 6 hearts). It makes extra hearts actually useful this time around. As it's 100% or 150% of your max health, all extra heart pieces included.
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Did I create all the badges?
On the WiiU port no. After about 250 hours, my external hard drive died and all my saved progress was gone. So I quit the game. But now on the Switch I do aim to create them all one day. When I have the time. The game is all about doing grinding though. Which is different to most musou games in a way. It's fun and yeah one day I'll do it.
How Hyrule Warriors is different, is that it's 10% story mode and 90% adventure mode. Whereas almost every other musou game is 90% story mode and replaying the stages in free mode. The last 10% is the other modes like special challenges and other things.