An adventure anime about cutesy monster creature that is coolly cute yet contains powerful supernatural abilities, human utilize them for sportive battles and many other things. This anime is mainly being a surreal battle comedy aimed at primary schoolers and/or preschoolers, story centered around a young boy dreaming to be the greatest pokemon trainer, traveling around the world to participate in many different battle tournaments.
(THIS IS IMPORTMANT!!! SPEAK WITH SUPER HEAVY EMPHASIS) However, I'm hereby providing a SERIOUS WARNING to any ignorant person before entering into this anime: If you are going to focus on the protagonist, you'll be disappointed again and again, especially the newest saga overlapping with its 20th year of broadcasting history. If you are going to focus on other human characters, you might be annoyed that they are either insignificant or useless, and too much to remember because almost every episodes there introduce a new character (mostly once-off dump away ones). If you are focusing on the pokemon creatures, you might also be annoyed that most of the time they are abused, if not by the human characters then it is by the plot. If you are going to focus on the story, then it is basically non-existent, because 80-90% of the episodes are one-shots without connection to any previous story, or poor connection to previous events even it is within the same saga, every 3 years or so the story will recycle (not revamp!), everything go in round circle.
So, if you wanted to enjoy this anime where minimal complaints shall come out from your own mouth, I suggest you watch it casually without putting your heart into it, you just watch it without thinking anything. The more interested you become with this anime, the less enjoyment you'll receive at the end of the day.