Regirock

Regirock is arguably the best tank in NU and inarguably one of the easiest Pokemon to fit on a team. Every serious NU team needs to be able to set up Stealth Rock, check Charizard, and check Tauros, and Regirock is an excellent choice for all three of those jobs. It also innately checks most other offensive Pokemon that don't have a super effective STAB move thanks to its remarkable bulk and respectable offensive presence. On top of that, it has access to Explosion, ensuring it will almost always at least trade one-for-one and preventing it from draining its team's momentum the way other defensive Pokemon sometimes do. Its only real flaw is its lack of a reliable recovery move, which makes it fairly easy to wear down, especially since it's often expected to counter multiple opposing Pokemon per match. That said, Regirock is a rock-solid pick for just about any team.