What’s the dimensions and filtration. Stocking a tank depends on many factors, how much water are you willing to change, is there a lot of filtration on the tank and how much will you feed the tank as with big eaters like that, the cost of food will be very exspensive. People say feeding one Oscar is expensive.
They should fit in a 1000 gallon, I don’t really have any experience with tanks that size so im guessing on the stocking but with heavy water changes it should work, you may be able to fit more if you run it on a auto water change as swimming space won’t be to much of an issue but it really depends on dimensions
That won't be big enough for the RTC but all the others will be fine, not having the RTC will open your options a lot and there are other alternative catfish .
I forgot about the pack they will be to big but I think the clown knives will be fine in that tank, without that heavy stock you could have a lot more options for other fish to add, if I were you I would create the tank around the peacock bass.