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)