I am doing more than four exercises, but those are a few that I can feel really work my abs. I think the Military press and squats are really good. Military press might hurt your shoulders.
Basically if you carry around a big bunch of weight with your free-standing body, your abs are working. Another one I've seen in a video that I might try because just looking at it I can tell it'll work is to grab a big dumbbell and hold it stiff-armed over your head and walk across the room. It was called a waiter carry, like you are a waiter holding a tray over your head.
For pullups which I can't do I use the assisted pullup machine. I also noticed a playground at the beach with a little curved bridge with a railing. I can use the bridge to get me into pullup position on the railing and try to hang on or lower myself slowly. The bridge gets in the way a little bit, but I can't figure out any other way to get my short self up to any other pullup bars. I can't do a pushup either, so I hold the planks longer and longer and move my arms further and further forward. Mountain climbers are also pretty good but I think I cheat when I do them and raise my butt too high.
Try some standing core work. Diagonal knee pulls. Boxer twists. Weighted sidebends. Core rotations. And planks, planks, and more planks. Crunches get a bad rap. They have their place on core training. Try this: 10 full range of motion crunches, immediately followed by 10 pulses at the top of your crunch. Repeat the sequence 5-10 times. With no rest in between.
I am a personal trainer and teach 2 core classes weekly. Change up your strength exercises constantly. The core is very adaptable. And get some good HIIT training (sprints) a few times a week. HIIT (high intensity interval training) is very effective on visceral fat. Sprint 30 seconds walk 30 again 5-10 times.
ms sage, I'll have to look up over 1/2 of what you said as I have no idea what it is. LOL
I have done HIIT on treadmill for sometime, but not sure how much I got out of it. I went for 27 min. 2 min walking at 3.5mph and running up to 8.5 MPH for a minute. Built up my calves but, not sure what else. Planks I did as therapy for a bad lower back. Got better at them but again, unless I could see them ??? and I know I won't see them until I lose a lot more weight. What I feel the most for my abs in the past was, from the 4 hour body, lying backwards on a small Swiss ball and doing crunches , arms parallel to floor stretched out then up to pointing to ceiling, with weight. Other was crunchs on Bowflex with aboutn 90 lbs resistance and side twists with Bowflex also.
I'll look up yours. Ty