Here's the pattern I use for Scootaloo's mane and tail! Sorry it doesn't have a bottom piece for the top mane but that's literally how I do it
This pattern will fit the filly pattern I have in my store without re-sizing: www.etsy.com/listing/174951254…
Simply sew each piece together. Leave a space open on the tail and turn inside out then stuff. On the mane only sew the spiked parts and leave the left side open, then place on the back of the head and sew it down. Download for original size.