Salamence

Mega Salamence's high-Base Power moves coupled with Aerilate and its solid base 145 Attack stat are very potent despite the high defensive stats that quite a few common Pokemon in Ubers possess. Its defensive capabilities from Intimidate before Mega Evolving and its very good Defense stat after make it a premier Ground-immune Pokemon on most hyper offense teams, and it can use this bulk to boost its Attack and solid base 120 Speed stats to further levels with Dragon Dance. It even gets reliable recovery in Roost to help it perform well as both a Ground-immune Pokemon and setup sweeper. Unfortunately, a nasty Stealth Rock weakness will usually shave off much of its utility it would otherwise have at full health, and due to the nature of hyper offense teams, it will often find itself without Defog support. Many Pokemon in Ubers also have the option of carrying Ice-type moves specifically aimed at Mega Salamence, which can drastically cut into its above-average survivability if they don't OHKO it outright.