Correction, that cite to Carnegie Melon does include that you are required to submit all subject tests.
Here is what i have found as to the only other colleges (in additon to those I mentioned above) that actually have any kind of all scores rule:
UPenn: requires all SAT and all ACT but has dropped that requirement for subject tests since it has gone to recommending and not requiring subject tests for admission.
Georgetown: all SAT, all ACT, and all SAT subject tests.
Yale: all SAT and all subject tests, or, alternatively to both of those, all ACTs. Like Pennit no longer requires but instead recommends subject tests for admission but still requires all of them to be sent if you send any SATs.
Stanford: all SAT’s and all ACT’s, but can send whatever SAT subject tests you desire to send
UC’s: ambiguous; require all SATs if you send SAT but do not appear to actually require all ACT’s or SAT subject tests.
Barnard College: ambiguous; Barnard claims its rule is “simple.” It is anything but. Bernard is one of those colleges that accepts ACT in lieu of both SAT and SAT subject tests. However, its all scores rule may require all SATs or all ACTs, or possibly all SATs and all ACTs, and may or may not require all subject tersts. Noteworthy is that Barnard is tied to Columbia University, which used to require all scores of all tests, but abolished that rule completely in 2012 and now accepts score choice.
Rice: requires all SATs but you can send ACTs and subject tests you want to send.
Tufts: requires all SAT scores if you submit SAT; no such requirement for ACT or subject tests.
Harvey Mudd: all SAT or all ACT, and all SAT subject tests
Pomona: ambiguous; requires all SAT if you send SAT; requires all ACT if you send ACT; but not clear on whether you have to send all of both or all subject tests
Syracuse: all SAT scores, no such rule for ACT (subject tests are not even considered for admission)