@PreHax The guide is missing Smoke Ball ;)
And why there are both Silverpowder AND Silver Powder listed, both with different spawns? They aren't the same item? Or maybe one of them is supposed to be Metal Powder?
I don't know how can you one hit Registeel, everyone who wants to catch a legend usually always bring a False Swiper. And False Swipe cannot one hit anything, especially when the opponent resist Normal.
Anyway, good luck, hope you can beat Nikola next time :)
Considering none of the types of the trees matches regular Rotom's type, my guess is that any of the trees can yield Rotom instead of the usual normal/dark/bug/grass, perhaps if the chain number is high enough.
You actually don't need to bring a lv100 team - you just need a team strong enough to take down a single lv120 Manaphy.
I brought a team that has 4 lv100 and 2 lv99 (hoping to level up from all the trainers around, but didn't get enough exp to go to lv100), and was still able to fight the Manaphy.