|so far I've beaten Kirby fighters on hard with sword and cutter. I can definitely beat the whole thing on hard eventually.|
Then I tried Dedede Drum Dash again for the first time since I first played the game... It's actually really fun, but requires a TON of concentration and precise timing. Getting the gold medals mostly just involves collecting every coin and not getting hit. There's also a bonus for not missing any backbeats that I never managed to get, but was able to get gold without that anyway.
Actually, looking at the guide on gamefaqs, there's also platinum medals that are very hard and most likely DO require getting perfect backbeats ontop of perfect everything else. The FAQ even says the platinum medal on the extra stage is just too insane and you should just give up on it.
I did get gold on drum dash level 4 a bit later after taking a break.