Thanks to all the collected cartridges we learned of many things and determined the exact position of all the Mews and even more details about how they were generated and with this one we also learned about a new initial Seed which has lead us to the Seeds of a couple of more Mews. The Mews that were placed in the Team. I was thinking about reconstructing the missing Mews as we might never get a chance to get them otherwise, but the problem is we never understood about these Trash Bytes and what
BIG UPDATE
All of the 426 Mews are finally together and even the mysteries about their placements are solved thanks to @Sabresite's newest findings.
A completely new Set of 5 Mews was discovered with the initial seed 0x5E2B. In fact it appears Mew #1, #2, #4 and #5 of the Seed 0x6065 (which I reconstructed earlier and we believed them to be in the Party) were deleted in order to generate the new Set. This leaves number #3 of Seed 0x6065 (to be found in Box 1, Slot 1) the only Mew of its Set