Having another viable grass type in OU has been healthy for the meta IMO. It helps keep rain in check and is a nice answer to Rotom-Wash (which still has a higher play rate than the Mon we are discussing btw). I think an outright ban of contrary Serp would be too heavy handed. I'd hate to see it deleted completely from the meta. Not to mention the backlash from the community as it is quite expensive to breed an HA Serp.
Although I think contrary Serp should stay, I can see where some of the other commenters are coming from regarding serps power level as it currently stands.
Introducing new items may have unintended consequences. I think there are some non-invasive easy ways to tune down Serperiors power level.
1. Remove glare from it's movepool. This will give faster revenge killers a chance to deal with Serp.
2. Reduce the accuracy on leaf storm. A drop to 80 or even 70 accuracy will help reduce the reliability of immediate contrary power boosts.
3. As previously mention release HA mons with infiltrator. This will help deal with not only Serps with sub but other sub mons as well.
I think implemention of one or several of these changes will help tune down the power level of Serp but still allow it a place in the meta.
