I've got a few things to share.
Fairyvania - a mashup of Megalovania and the main theme of the anime
Fairy Tail.
Burning in Hell - a remix sort of based off of "Waters of Megalovania", a remix on YouTube.
Some Undertale transcriptions:
Unydne
Run!
Metal Crusher
Clowning Around - what has basically become the CinemaSins theme song. If you haven't seen a CinemaSins YouTube video and you're a big fan of movies, you're missing out. Transcribed by ear.
I'm not familiar with Fairy Tail at all, but "Fairyvania" seems to have very accurate, Megalovania percussion. The only jarring thing about it is that there's one section of Megalovania - tracks 3 and 4 at bar 28 (plus the other section with this part) - the harmony is sounding off for some reason. Maybe it's the octaves; I haven't checked the actual notes myself. I don't know if this is a reference to some other part from Fairy Tail, but if it is, it's probably better just to keep it all Megalovania there.
As for your Undertale transcriptions...they sound good; the inaccuracies are very minor.
The starting notes in Undyne are pretty close; just up the fourth note in tracks 1 and 2 by two steps to the G in bar 000, and up by one step in bar 002 for those two tracks at the fourth note, and soforth. I find the Snare too aggressive in this; it overpowers the music too much. For multiple Snares played very fast in a row, consider playing around with the volume enveloping so that they're not just a huge thing of pounding noise that so happens to occur every two bars.
For Run!, I think it sounds much better without track 5. I also feel as though the HiOpens could be at a much higher octave, or at least at a softer volume. Right now, because they're low, they tend to leave behind a lot of noise and less of the "cymbal" sound heard in the actual song.
Metal Crusher...I actually love how flowing the lead is and kind of dreamlike. Yeah I'm hearing off notes here and there, but the sound is kind of pleasant, so I'll give you that. I did a
Metal Crusher ORG transcription a while back, and it may help in adjusting the notes.
Good stuff.