I totally agree with what you had to say about Tropius and Parasect. They are over-centralizing the entirety of OU, but they're not alone. Shuckle is the most defensive Pokémon out there, and quite frankly, when it wields an amazing STAB like Stone Edge, it's unstoppable. Able to fire off massive 244 HP Final gambits, KOing the likes of Eviolite Abra at full health, one of the many under-the-radar threats of OU. Of course, that barely scratches the surface of some of the even more should-be-ubers. They are vast in number. Among them are things such as Shell Smash Macargo, Speed Boost Combusken, and especially the dreaded Metal Burst Bastiodon. I trust you to do what's right. Purge OU of these disgraces, achieve balance.