Kylo Ren is just a pussy tormented dude with no martial art training what soever ! He is great at telepathy and other trick, but his light saber is just here to look cool and he is quasi incappble of exploiting the edge of his weapon against experienced duelist.
Grievous is a ****ing damn Kaalesh warior he kick his ass even before his cybernetic reconstruction !
"Kylo can win if we are talking about pre-cybernetic post shuttle bombing Grievous."
XD post shuttle bombing, he also win against vador pre-cybernetic post you were destined to bring the glaxy to the light no to the darkness !