I recently aquired this Reverse Holo Slowking from Southern Islands. Its in extremely good condition and the centering is near perfect. I decided to consider having it graded so I started to inspect the card and noticed that the back of the card is off center from left to right and is larger on left and smaller on right. Big enough to notice just by glancing. And the front is near perfect. Im wondering if anyone else has seen this with this set? Should I have it graded as an error? Whats this error called? I understand it could be Misaligned Fusing when the entire sheet was created. But ive not found any others like this. Opinions? And im extremely confident that its not fake. Zero signs of a fake. Please help! It may be 1 of 1 and could turn out to be quite valuable and I could definitely use that!!! Thanks!!
This is not uncommon. The front and the back are printed on different passes through the offset printer. The centering on the front doesn’t have to match the centering on the back
This is how you can also end up with cards that have an upside-down back
Thank you for the fast response!! Im interested in the rarity of this and if it will affect its value. Is it submissable as an error?
Hi!
Front and back centering of the card do not always have the same centering based on the printing process of the card. In this case, the back centering looks a little more off than the front but this is a relatively normal occurrence.
No, this is not an error.
Unfortunately it is neither rare nor desirable
Thank you guys! I appreciate the feedback. I thought i stumbled on something rare for this already low count card.
Just because it isn’t a rare error/misprint shouldn’t detract from how great the card is 
Southern Islands is an incredible set with great cohesion and artwork. The reverse cosmos holo patterns are amazing too!
I don’t grade at all, but the back looks like it has edge whitening that would prevent a 10. You can always try to post more pictures if you’re curious to see what others think it would get grade-wise.
Closer to PSA 8 than PSA 10
Yeah i figured an 8 as well, I adore the card and would like to collect all the reverse Holo’s from the set. I just thoight it was an error as ive no experience with this specific mis maych before. I have WAY more experience with modern and have only recently gotten into vintage cards since I started buying and reselling. A friend recommended to come to here and told me I would get great responses and he was right. I really appreciate it. 
Welcome to the dark side! 
The card is absolutely sick regardless, definitely a great “smaller” set to collect
I’ve recently Mastered Fossil and once the Dark Machamp shows up in the mail, I’ll have Team Rocket done. Its been alot of fun relearning the older cards.