I'll say it right now.
Fatty Whale is by far my least favorite.
Too durable for what is a bosh rush boss, and especially with how this game is meant to play.
He takes too long to properly damage and has attacks that have very wonky hitboxes.
And as the third part of the Holo Defense battle, he just comes off as mean and unfair.
Trust me, I wouldn't be as hateful towards him if he was a standalone boss.
Still can't get past him.
You can practice fighting Fatty Whale and the other Holo Bosses as standalone bosses by going to the right of the boss door. And for a few Fatty Whle tips, he only has a hurtbox when he's jumping, when he's spinning and going from one side of the arena to the other, you can safely attack him as much as you want while staying inside his sprite. Also, don't forget to use Bronto Burt for valuable chip damage when he's jumping over you, it may not seem like a lot of damage, but it does help.
Trust me, Fatty Whale used to be much worse. In the first versions of WK, he had way too much health, resulting in the Time Attack requirements for HDAPI being basically impossible.
The only thing about Fatty Whale's three attacks which changes is whether his waterspouts during the roll attack are pink or not. Thus, you can learn the exact positioning to avoid each attack (e.g. for the backflip attack, I used to always stay in the middle and parry the middle spout which is guaranteed to be pink, but I later found a spot between FW and the left/rightmost spout's extended hitboxes which was much more safe)
