RTree
Plantera
yes
A fellow humanoid of culture I see.
A fellow humanoid of culture I see.
OCTOPATH SPOTTEDGaldera from Octopath Traveler 1... and 2. He's worse in Octopath 1 though, because you need to go through a whole 8-boss boss rush before fighting him... every single time you lose. Not to mention the bosses before him are ridiculously easy compared to him, and so by the time you reach and eventually lose to Galdera, great work! You just wasted two hours of your life. You need all eight characters to be as optimized as possible for even a chance at winning--his first form is just as hard as his second. The highest level area to level up in is level 65... when you need eight characters to reach at least level 90! It took me over an extra 12 hours of just grinding XP to beat this boss! It's like an old pokemon game, but if you were EXPECTED to reach level 100! MAYBE you could try to cheese him with Chubby Caits, but that would only work for one form and be even worse than grinding all those levels...
In Octopath 2, I haven't actually been able to beat him yet-- I just don't have the motivation right now... But fortunately, grinding XP in that game is significantly faster and you don't need to do a boss rush before fighting him.
His theme is a banger though
And I know even saying the B-word when talking about hardest bosses is embarrasing... but yep, Bowser. Specifically, the giant dreamy battle near the end of Mario & Luigi Dream Team. The attacks are telegraphed horribly and require intense tiny touchscreen timing... not to mention... the entire battle eventually becomes 3DS motion controls with no way to toggle it... The worst part is that if you lose in Hard Mode, you have to watch this stupid, long unskippable cutscene every time you start over...
Some honorable mentions:
Man-at-Legs from Pikmin 2
Pyribbit DX and... flowery woods DX... from Kirby Triple Deluxe
Inner Agent 3 from Splatoon 2
Water Lily Siren from Shantae & the Seven Sirens (esp. with mobile controls)
Minecraft bosses, period
The first Gromba from M&L Dream Team Hard Mode... I'm not even joking...