Bro this reminds me of Ben 10 and you have no idea how big of a compliment that is.
I like this but it's too repetitive and I don't think really is anything like Undertale (I haven't played / watched the others) you have a great ear for what sounds you want and your mixing is impressive for the first track you've made.
Blue Lava has made some great suggestions already but in this genre I would consider fading in and out an instrument that plays like one note in sixteenth note patterns to add a little movement. More percussion also would help with the groove.