u/Annual_Bear_5072

-2010s

-animated show with an artstyle similar to voltron

-characters had gadgets on their arms/wrists

-monsters(not sure thats what theyre called in the show)

-characters would participate in a contest inside a large real life arena/stadium with themes usually like a forest, swamp, the like

-inside these stadiums, characters would use the aforementioned devices to capture these "monsters" and fuse them together(needs 2 monsters to fuse) then enter combat with other participants to win

-pretty sure the male mc had a purple companion who was one of these monsters and it was sorta like an octopus(?)

-not cards or robots

-the order in which you fuse the monsters matter in what you get