ITT: That Pokemon you like and always try to have on the team yet rarely gets sent into battle because you're reluctant to use it
Tyrantrum and Porygon-Z for me. They're some of my most favorite Pokes, the latter being the top fav but I keep getting the feeling they'd be OHKO'ed in PvP battles so they end up sitting in the sidelines. They're far from weak, but I probably just don't want to see them getting destroyed.