I can try:
1) Bci cage size should be 4x2x1. They seem to thrive at this size of cage. Easy to build too (efficient use of wood).
2) Ball Pythons are good in 32" x 18" x 12".
3) Corns will do well in 32" x 18" x 6".
4) Leos will do well in just about anything.
5) Beardies? Haven't a clue. A quick search on the Internet will bring up a TON of sites with care sheets. A good portion of those should have minimum dimensions.
(sizes are in the order length x width x height).