It 0-shotted it... but incorrectly, right?
Gloober Zoo flomps gloober Bat on turn 1. Gloober Bat flomps gloober Blue on turn 2.
Answering '4' seems like a total guess, maybe based on there being four steps, or 'Blue' being mentioned in step 4.
The replies to your post seem to assume that the answer is correct, but it is actually demonstrating a lack of step-wise reasoning.
My reading is that on line 1, no action happens, because Roy isn't yellow.
I still don't see how 4 could be a correct answer, could you post a plausible sequence of turns where Blue turns yellow on turn 4?
1. Zoo
2. Zoo, Bat, Crystal
3. Zoo, Bat, Crystal, X-Ray
4. Zoo, Bat, Crystal, X-Ray, Blue
If I understand you correctly, you are applying only one of the steps each turn, in order, which contradicts the instructions by flomping different gloobers each turn.
It is also guessable in multiple ways which is unfortunate. "There are four steps specified so I guess it happens on turn four." is one invalid way of getting the same answer.