So uh, i never came back to share what happened with my modern subs to CGC.
DS and 3DS games are very loose in the holder. both the blister is loose, and game inside the blister is loose.
When I reached out to CGC to let them know so they could fix the dang thing for future customers (I wasn't even asking for a refund or reholder, because I knew the outcome would have been the same), they told me "the cases aren't meant to be shaken." no word on whether they're telling anyone about the issue. Just "don't shake the game."
i mean, i'm not sure how else i was going to figure out the games are loose, but cool.
anyway, if you have DS/3DS, don't send them to CGC. send to Wata or VGA. who knows if CGC will ever fix their holder.
anywhere, here are the games i ended up grading with this issue, and will likely bust out in the near future and submit somewhere else lmao
Metroid Samus Returns 9.9 A++ (pack-in)
Metroid Samus Returns 9.8 A++ (pack-in)
Mega Man Battle network Double Team DS 9.8 A++
Super mario 64 DS 9.6 A