Id incorporate some lower back either Back extensions or supermans, also some Hip Bridges to hit the hips a bit.
As far as the abs go theres a lot you can do to tax the abs i do them usually 2-3 times a week since there worked in the main compound lifts like squats as well. I'll list some of the ones i do below but if your doing variations of crunches id aim for 20-25 reps for each exercise and about 200 total reps.
Hanging Windshield Wipers (personal favorite there tough but burn like hell)
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Russian Twists
Reverse Crunches
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If you have a partner i love these
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Those are just a few of the ones i do but like i said before don't neglect lower back, and hips a lot of power is driven from those and are big parts of the core.