This while not wonderful doesn't make it seem like I can't use their content. It seems like my best course of action would be to make my novelties a bit more stylized and change the name.
This is not legal advice and I am not your attorney. If you want legal advice, retain counsel licensed to practice in your jurisdiction. With that out of the way...
Attack names aren't going to be trademarked, so you're safe there. As for everything else, here's a decent rule of thumb: if you do a Google search and the trademarked/copyrighted thing is the first hit, avoid it. "Mudfish" is fine. Stylized novelties are fine.
That all said, this whole thread would be discoverable and evidence against any defense you made that this wasn't derivative of their copyrighted character.
That's not to scare you, that's just the reality. However, unless you start selling tens of thousands of kits, you're probably going to be under the radar and not worth their time. The further removed you make it - calling it mudfish, not using pics of the 'mon and not referencing "Pokemon" - the less likely they're going to come after you.