This is a fairly obvious suggestion; I'm sure it's been thought of before. I just haven't seen a whole lot of it.
Think: "the Wind Waker's Red Chu Chu counter" when you read this. Imagine a series of counters on the subscreen (Passive or otherwise.) which would ... ... ...
...
It strikes me as I type this... ... all we really need for this, is the ability to include the z items in the subscreen as counters, and the ability to attach a script to z items. :shrug: Silly me. >.>'