I was searching Google trying to find an anime I saw 6 to 8 years ago and found this post from late 2019 and no one successfully answered the question so I'm reposting it, I'm pretty sure that the post is talking about the same anime (if not the plots are near identical).
Here is a copy of the original post:
There is a group of friends that have those cards which can activate some monsters and they can battle other people like that. In that anime there are Death Eaters OGs that were a cult like group with tattoos. A brother of one character is in that cult and then when needed he confesses and tries to help them save the world from that cult organization. The head of the cult has this one monster that can suck in other monsters and take their powers, killing them in the process. The group has to stop that monster somehow. The deaths of those monsters were extremely sad as characters were bonded with them emotionally and the development of characters is amazing.
When I watched it it reminded me of Pokemon but with cards instead of Pokeballs, and I'm pretty sure that the main character had a monster similar to Pikachu and could fly by spinning its tail.