Just been in touch with PSA because i’ve had a couple of concerns about cards moving inside the slabs, and getting damaged (especially in the post). I just had a response from PSA stating that Pokemon cards do infact move in the slabs…thoughts? 
"Hello *******,
These cards will move very very slightly in the holders, but it should not be anything drastic. If you have any further questions, please feel free to contact us.
Thank you,
Veronica Lopez
PSA Customer Service
Collectors Universe Inc."
The movement is so slight it should not matter. Just don’t violently shake your case.
Yeah but when things are being shipped and going through the postal service surely they’re shaken around a lot then? Even when you receive your graded cards directly back from PSA they’ll be shaken about surely? 
I took a cheap low graded card that showed lots of movement and shook it vigorously for about an hour on end to see if it changed. Nothing was going on so I stopped. I used to be worried about it but if that didn’t seem to damage it then I thought nothing due to shipping would.
Years ago we had that concern so we had the cards left in a penny sleeve then slabbed. It stopped the movement but looked awful.
I’ve never seen proof anyway that with normal handling the card inside isn’t safe.
I have noticed half of my PSA cards are loose in the case. It sort of bugs me but I haven’t noticed any damage caused from that.
Hmmm interesting…perhaps i’ll buy a cheap PSA card and do that myself and post the photos on here of before and after 
The old PSA cards inside the sleeves looked awful. I had all of mine reholdered as I couldn’t bear it 
Well i’ve just got a PSA 10 card for the experiment. When I receive it I shall conduct my experiment… 
I’m shaking one of my PSA cards and it’s not loose in its case… Maybe it’s the newer holders.
It’s some but not all of the cards.
Now we have to complete PSA 10 sets in loose AND adequate slabbed cases.
Lol
I only have a couple psa’s s far but neither of them slide. However I haven’t given either of them a crazy shake either. I have a cheap bccg card though that moves around like crazy. Would never recommend those to anyone
I just got my first PSA card recently (a PSA 9 4th Print Hitmonchan) and it can slide in its case.
I noticed a small gap on the top between the card and the plastic side, so curious, I shook the case very hard downward once and when I looked again, the gap was now at the bottom.
I don’t see any gaps on the sides, so maybe the cards only move up and down. Maybe my card or case is just strange… lol But all I know is I will never shake any PSA cases again…
Since my previous post I’ve acquired more Psa cards and one of them is actually pretty loose and it’s a gem mint 10. I agree this is annoying and Psa I feel should have re sealed it there before sending it out to the recepient (I bought it second hand). Seems like some must randomly move more than others
Well I can confirm after buying a PSA 10 card and shaking the living daylights out of it, putting it in my pocket for a week there was no damage done even though there was some movement.
That’s good to know. Although its still annoying some of them are loose. Oh well
Well PSA have screwed up big time with my latest purchase…a 9 Mint Kamex Error…the thing is moving 1-2cm up and down!!! 
Send it in for a recasing.