Firstly, + means it's a strong impact on opponent, ++ stronger, +++ is very strong defeat or almost defeat.
Nite Elf is black, so use dragon type with green, white, cosmic, rainbow. It is also a super rare, so try to use a super rare, expired or unbreedable against it for better chance. Dawntree is a green and super rare, that's why I chose it, even though it's only level 6.
So with your dragons, find any super rare, expired or unbreedable with those colours. Say Pegasus, fuzzy, pearl, light, cosmic, Saturn, rainbow... Who knows your forest or emerald may beat it some players beat it with Forest BM, Forest BB.
Good luck