I like forretres because it gets 3 entry hazard moves: spikes, stealth rock and toxic spikes. it also has pretty good defence.
but probably the best one is shuckle, with the best defences in the game.
252 def 252 spD 4 HP
and it gets sticky web, stealth rock, knock off, toxic, bind and lots of other useful moves, obviously we are focusing on sticky web and stealth rock.
plus, you get to boost defence with contrary shell-smash