The PokeChecker would be a tool to check what pokemon the player has in their party. I would think something like a preasure plate that only emits redstone from oneside if the required pokemon are present and the other if absent.
I would imagine this to use a text input and check for a pokemon in their party. This means we can make scenarios that require pokemon better controlled. For example obtaining regigigas could be made only able if they have the 3 golems, or if they try to go on to route 1 without a pokemon Oak can materialize and tell them it's dangerous to go alone.
Other Better Tools for Map Makers Suggestions:
Like Game HMS:
http://pixelmonmod.com/viewtopic.php?f= ... HM#p186948
Multi Leveled Trainers:
Long Distance Battling: