Serperior is a pure Grass type, is the fully evolved form of the Grass starter Snivy, and to me has probably the more appealing design from the Unova starter final evolutions. Also, I find Serperior is the better starter in terms of both in game & competitively as it has solid abilities, decent stats & a decent movepool. Serperior tends to do best with Leaf Storm + Contrary combination in competitive, but in game most the time you have to rely on Overgrow ability, which isn't as great. Anyways, Grass types starters usually tend to be my least favorite amongst the generations, but when it comes to Unova, the Grass type starter is hands down my favorite, hence Serperior being ranked this high. However, I just like the other 4 better, so had no option but to rank Serperior 5th.