A couple updates on this situation. I sent another message to eBay and they sent a reassuring reply:
"Thank you for contacting eBay in regard to case that you filed for the Pokemon tropical mega battle (item # 192033013357) that you recently purchased here on eBay. I reviewed your case and I understand that you suspect that the card that you received from the seller is not authentic Nintendo Pokemon card. I’ll be more than happy to help you out with the case.
This means that you will be refunded for the full purchase price plus the original postage costs (if any). At this point, we have gotten in touch with the seller and asked them to provide a shipping label or issue you funds through PayPal to purchase a return label. We have given the seller 5 days to successfully facilitate the return with you.
While the case has been put on hold for 5 days, I strongly suggest for you to ask your postal office the amount that you need for a traceable service for return and inform the seller about it. In this way, your seller will be aware of how much they need to send in to your PayPal account to facilitate the return.
You can also contact us again as soon as you received a shipping label from the seller so we can take the next action for this matter.
If after the given timeframe and no resolution has been reached regarding the return shipping, eBay will then proceed with a final decision regarding the case base on the information we have available on file. We will get in touch with you within 24-48 hours from the time the hold is released.
While I was reviewing your case, I can’t help myself but appreciate your effort of letting eBay know your issue and having us mediate on the situation. You have just taken the right step to ensure as a member of eBay community is always protected.
Please let us know if you received it or not. We will get back after 5 days to take action on the case. If your seller has not responded with an acceptable resolution within the given timeframe, we will give your refund (includes the original price of the item and original shipping fee if applicable).
I know that this information will help us to work things out with your trading partner. Thanks for your cooperation and patience regarding this case!
Sincerely,
eBay Customer Support"
This morning a decision was made in my favor. I was refunded in full. The seller never replied to myself or eBay. I’m actually glad I didn’t have to try and send it back. I’m also thankful eBay was able to expedite the case by 5 days after my second message. Hopefully this can help anybody that runs into an issue like this in the future.
Edit: Also thank you @nuttun for the supportive words!