Adding custom trainer battles/events to a Pokemon Black RomHack - Help needed

[Estreth]

Hello everyone! I was just wondering if I could get some assistance. I've been working on a RomHack for Pokemon Black (working title Pokemon Black+ or Black Plus) which was initially just a simple "changing wild Pokemon locations and Trainer battles while still keeping faithful to the original B/W vision (That being only 5th gen Pokémon available during the main campaign)" project to a "Ooo lets sort out stats, learnsets, place some more items on the map, such as Heart Scales, as well as add new trainer battles and events/side quests/optional content to the main campaign" project, in other words, throwing myself into the deep end (I should mention that this is my first RomHack. I've always wanted to make one, Black and White are my favourite Pokemon games and a month ago I finally got the motivation to truly start this project and I've been learning as I go)

So Edited Wild Encounters, trainer teams as well as placing items I've pretty much sorted (Well it is more of a hodge podge kind of approach, take the event for a Heart Scale/Leftovers on another map and then copy paste it in another area sort of thing) but one thing that has become a major roadblock for me is adding events to the game, such as custom Trainer Battles. Scripting is completely new to me and I have been doing my research and learning steadily but I'm really struggling marrying up the adding overworld sprite and designating a script for them in a Hex editor. I've just been using a template script to learn how it all works but even when I follow the template to the letter (or rather number) and try to assign, nothing is happening so I thought I would ask if anyone would be able to go a little more into detail as to how I could make it all flow and, well, work.

I do have a bit of a laundry list of events I have planned and would love to implement but I don't expect anyone to answer it all at once of course;
Some examples are;
- Adding custom NPCs that give certain items after defeating them. Such as a Black Belt in Pinwheel Forest that rewards you with a Muscle Band and a Lass in Castelia City that rewards the Wise Glasses (kinda like how Rangers reward Berries after defeating them)
- Adding NPCs and overworld items that give RageCandyBars and then having an NPC (The Zen Master) come up and battle the player after they have either caught or defeated all of the Zen Mode Darmanitan in Desert Resort which, upon beating him, rewards TM35 Flamethrower (I've been able to move TM13 Ice Beam to Challenger's Cave and made it accessible during the main campaign, balancing levels of course. TM24 Thunderbolt is untouched) 
-Changing the Zoroark event in Lostlorn forest to not need the Shiny Event Beasts. An idea is having the Lock Capsule be in the caravan/trailer and then the Zoroark runs up to the player, the illusion is broken and then a wild battle with Zoroark starts. Then can take the Lock Capsule to Mr.Lock and get TM95 Snarl
-Changing the stock that Pokemarts sell, more specifically the 2nd clerk in some cities and the Herb seller in Driftveil Market and add berries and Battle Subway TMs to the stock they sell. There is a program and NARC file in B2W2 but I have found NO info on how to do it in B/W.

If anyone could help me with this, such as running through how I could do these while explaining it to me like I'm 5 I would be very grateful!

Thanks for reading and Merry Christmas/Happy Holidays!