suggestion: separate cart, box and manual rarities

[Lincoln]

credit to nintendoage for doing this. it seems like a good solution when cart and box availability are different by a wide margin. for example, see the sears checkers thread. the cart looks to be obtainable, but nobody can find a box.

 

a major point to decide before implementing this is if boxes and manuals are to be rated within the existing cart scale or have a new scale for each category. if we rate boxes against carts, there is no box that is as common as a combat cart. so there are no R1 boxes. the most common box might be R3 or R4. going the other way, the most common box would be the standard for R1, and all other boxes are rated against that. my concern here is that it might be confusing to have an R7 cart listed with an R4 box or some odd combo like that.