So it's not like pure randomness, but the percentages vary upon location, with the possibility of some locations having only one Attraction appear. So for example, Magic Mountain might have a 30% chance while in Thebes, but 100% when fighting the Rock Titan.
And given that Nomura described Attraction Flow as "a colorful presentation without button mashing. You can enjoy a visual treat on the screen." it sounds like Attraction Flow is an invincible attack with little to no input, so even if you don't get the one you wanted, the randomness doesn't appear to be detrimental.