Ever make a little mistake or choose to abbreviate and have a dude jump down your throat?
Dude's just waiting to make a correction? Prove his superiority over you and auto correct?
How much does it matter, the occasional error? The infrequent slip?
He is waiting, though, hiding in the tall grass. He'll leap out at you as soon as he gets a chance. "You're wrong!" "Write better!" "You make my eyes hurt!"
This is how I see Serperior. Obviously he's trying to cover up for his own perceived shortcomings. Maybe he was bullied in high school? Maybe he has spent his whole life slowly becoming an internet troll?
Out of your Generation V starters the things to remember about Serperior are: Dude is Grass-type. He has the most weaknesses of any of the starter types. He makes up for this defensively - he has the highest Defense and Special Defense base stats of the trio. Finally, he is the fastest - quite ready to leap out and correct you with alacrity.
Serperior's base Speed stat of 113 is his highest and puts him within the top 10% of Pokémon for Speed. Defense and Special Defense are balanced at 95. HP, Attack, and Special Attack are all tied at 75. Outside of his Speed stat Serperior isn't winning any contests. If you want to use Serperior as your starter, looking for a particular nature, you can do a Vinnie soft reset to try to get Timid or Jolly to boost Speed, Bold or Impish to boost Defense, or Calm or Careful to boost Special Defense. If you want to build up Serperior as a Grass-type wall, distribute your EVs appropriately - possibly giving him a bit more in HP. Keep in mind you can breed Serperior if you want to try to get a particular IV spread.
Another thing to consider is Serperior's best attack, Leaf Storm, is Special category. You may want to do your best to build up his Special Attack. I think including Giga Drain is also a great idea. Serperior can also learn Light Screen and Reflect to leverage his high defensive capabilities. An additional move to consider is Magical Leaf - it is a Grass-type move that is not impacted by changes to accuracy and evasion.
I really like the idea of having Serperior hold a Big Root. While it does not increase the amount of damage caused by Giga Drain, it does boost the healing that you receive from it by 30%. Keep in mind that all types take damage from Grass-type moves so you will always get something plus when you use Giga Drain.
The current Serperior in the TCG is not very widely used. Notably there is a Serperior included as a secret rare in the Dragons Exalted release. With a Plus Power attached, it will OHKO Terrakion, one of the most popular cards in the current format, it will two shot a Terrakion EX and Keldeo EX. Both of these cards are increasing in popularity, especially with the Boundaries Crossed release coming soon. The difficulty being, of course, that Serperior is a Stage 2 Pokémon so it can be difficult to get him started.
Honestly, I have never been a fan of using a Grass-type starter, not even that super cute Chikorita. I don't make the rules, though, different serpents for different folks!