Essential processing: This is what I have observed with my pre-sessional students from the most difficult to least: Paraphrasing> Harvard referencing style> passive voice.
As Paula has said paraphrasing requires a combination of different skills which can be challenging for some students. Regarding referencing, it might be the first time students are learning/using references and it takes a few lessons/feedback for them to cite sources appropriately, and understand the reasons for doing it. Students usually seem confident about the passive voice that doesn’t necessarily mean they can use it efficiently.
Generative processing: I agree with Sue that learners have their own approach to consolidate their knowledge. I think the activities on the Wordwall website could help students at a very basic/elementary level. Maybe, It would be necessary more complex activities to help students store information in their long-term memory.