It’s like in literature if someone could patent the idea of a detective investigating a murder.
How could the "pokemon-like" genre even exist if you couldn’t create a game that uses “summoning and battling characters”?
Even worse, that description alone applies to multiple genres... JRPGs, or even fighting games with multiple characters (something like Marvel vs. Capcom) could fit that description.
I can understand intellectual property rights for very specific technical implementations (for example, the raycasting technique used in Wolfenstein 3D) but you shouldn’t be able to patent the concept of the first person shooter itself. That feels more like restricting freedom of expression.