I know you guys are hesitant to think about Stygian Dirge and Mischief of the Yokai, but I've tested them and believe it or not they've worked. Mischief of the Yokai especially has helped me to win games against Dino Rabbit, Hieratics, and E-Dragons. Let me address things one at a time now.
"You mentioned XYZ monster but really, a lot of people run 3s and 4s, what it really screws with in my oppinion is Syncro, it lowers the level of both the tuner and the monster making it impossible to do anything"
Yes, several people run Rank 3s and Rank 4s, but more often than not they have more crucial rank 4s than 3s (or at least from what I've seen). Played at the right time, you can stop a Tour Guide play, a Dolka/Laggia play, Dragossack or Big Eye play, and many more. While your opponent may have an out (more than likely a rank 3 for a rank 4) it still won't be what they originally wanted to play and they may end up misplaying as a result of a shocking play. And Mischief of the Yokai has the ability to reduce all levels by 2 or just lower one monster's level by 1 for uneven levels. And yes, it's good to stop Synchro plays too
"the level changer traps are a good call in the right situation but can also be a bit situtional at times with them being traps also needs to be drawn and a turn to set-up."
Yes, they require a turn to set up, but so do a lot of cards. Mischief of the Yokai has 2 benefits over other cards though. 1 - chainability. Traps like mirror force and dimensional prison are prone to being destroyed or getting Lanced. Speaking of D Prison, that's losing ground too with E-Dragons getting pluses off of being removed from play. 2 - You get two uses out of it and the second use may be better than the first. By lowering the level of one monster alone you're really disrupting a play.