My Goal
I am creating an event on my server using CustomNPC's that checks if you've defeated a very specific trainer. I can (or could) do this by simply following the specific steps:
1. Talk to the CustomNPC.
2. CustomNPC initiates a battle using /pokebattle [Pixelmon Trainer Name] @dp
3. PixelmonNPC drops "PokeBall" item.
3. Speak with CustomNPC again, NPC's dialog options update if player has a PokeBall in his or her inventory allowing for the next dialog option.
4. By updating your CustomNPC's global "PlayerData" with the new dialog option that opened up after receiving the PokeBall item, you can now cross the "Border" block that had it's availability set to the updated dialog after the battle.