Here's what rhymes with ineffectual.

Consider these alternatives

ineffective / effective indecisive / decisive powerless / flowerless feeble / people uncoordinated / coordinated uninspired / desired derided / decided ineffectiveness / effectiveness tyrannical / mechanical inefficient / sufficient futile / pupil counterproductive / productive misguided / decided imperious / serious incapable / capable inexperienced / experienced unresponsive / responses