Regarding the difficulty...

[Katana Puffin]

Is it just me, or despite having put the game in easy and having spent a lot of credits to upgrade the character (level 19) and the red sword almost to the maximum, I can't get to the last boss?
I barely beat the rose, what am I wrong?
Sorry for my bad English but I'm Italian, if you can can you write in simplified English?

[Toxi The Vagrant]

Best advice I can give without added specifics:
Great thunderbolt or unlimited fire stacking best damage overall.
Don't generalize elements too much.
Speed is war.

[sombombud]

Dash/doge more often
don't spread out your cores/gears too much
play to each character strengths
Don't try to speed run bosses.

[Katana Puffin]

Ok so I need to focus more on thunder and fire cores? Just this?
At certain point enemies become too though to defeat.
Even the boss, is very hard at my point

[sombombud]

if you pick fire, ice or lighting, its fine.
i personally like Ice.
if you see the same gears in crates, grab those vs spreading out your build too wide.
its hard to say exactly where your struggling without seeing you play ha