There are 119 numbers in the grid and on the "all species" page there are 54 species. The number of the grid-number is uneven, so it can't be two buttons per species for a number and there are nowhere near 119 species, so it's not that a number equals a species.
I'm tired and it's getting late. I think I'll give this one up and just answer "Grundo". He's a grundo afterall, there are Grundos born on Virtupets and maybe the grid doesn't mean anything. If I'm wrong, it's just another week without some tiny amount of NP