Why do Mons series always have to be based on things that already exist? Think about it; it's as if, for instance, someone thought that marbles would be more interesting if they were being shot out of plastic humanoid cannons. Or, how about we go further? Why not just have the marbles transform into little monsters?
I've come to the conclusion that you could make a Mons series out of pretty much any random thing - tops, yo-yos, piñatas, Tamagotchis, those things you get in vending machines, Pogs, food fights - pretty much all you have to do is either turn some random thing into a monster, turn it into something that controls monsters, or turn it into something that contains monsters.
Heck, I could probably create my own Mons series right here, right now. So, let's start with a protractor, but let's have it fold and transform into monsters. Now, let's add dice, attachable weapons, things that light up, symbols representing different elements (let's make those fire, metal, water, wood, and darkness, always gotta have darkness so the bad guys have something to use), and the protagonist can be an overconfident preteen who uses the big red fire dragon thing. As for the plot, he's trying to catch 'em all, and the villains want to destroy the world because... they're evil. Oh, and they also want to capture the hero's creature, plus every single creature the hero encounters. Now just add every single Anime cliche, and we're done.