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There was a chess board battle in the Genesis game Shining Force II, is that what you're thinking of?
hmmm, It sounds like how some "monster in my pocket" miniatures were sold, sometimes they came in small buckets of pink slime. could it have been the video game of this?
Only ones I looked up for that were side-scrollers and didn't match otherwise.
I think its Beast Wrestler/Beast Warriors
I remember one Genesis Game, I played it on Sega Channel. Anyway it involved selections of monsters and a fight on something chessboard like. It was isometric or top down. When you defeated an enemy they were added to your selection. There was a part in the game which allowed for merging of monsters in (a) big tube(s).. I remember a pink ooze being fused with some monstrous humanoid and the result being roughly that monster covered with the pink.