First season is pretty great, fantastic even
Season 2 isnt AS good as season 1 but it has some nice elements and is still good enough, especially because of the new villains
Season 3 is alright, it feels rushed but that's propably because of the low viewership at this point, it has some nice elements but its my least favorite one but its also the shortest
Fights are great, they feel closer to kaiju battles with the Monsuno's large sizes rather than Pokemon battles
The only bad part is that the animation sometimes feels like it's budget isnt too high but the fights have very cool attacks
There are only minor gripes i have and most, if not all of them are towards Season 2 and 3
However all "bad" aspects are negated because in Season 3, a guy uses a sandwich as a Monsuno core
10/10