[Scripting Question] Script that gets called when certain pokemon evolves

Hello I'm still a noob at using essentials and I'm trying to get a script to auto check if a certain Pok?mon species in the players party has evolved after battle even if the Pok?mon isn't in slot [0] in the party.

My finial goal is to have the player receive a Pok?mon that's part of the games story. This Pok?mon will follow you like in heart gold (but only this Pok?mon not others). And the sprites need to be updated when that certain Pok?mon evolves along with allowing me to turn on some switches that progresses the game when it does.

I already have the following part taken care of (kind of) using dependent events the only problem is changing sprites when the Pok?mon evolves.

If a script like this already exists could you gladly post it here or give me some tips on how to write a script that could do this task?
thanks in advance ~Fang

You can use pbHasSpecies?(:[insertnamehere]) to check if a pokemon is in your party. Regardless of slot.

My plan was to use that on the dependent event, and have it turn switches on/off or change variables to have it change into a new event page so that the graphics and common event it triggers can be changed.