With Quagsire / Sandslash / Nidoqueen / Gastrodon absolutely everywhere - they're relied on to deal with so much stuff, particularly Fighting- and Electric-types - offensive Grass-types can be really, really scary.
Cacturne is very hard to stop after a Swords Dance - those powerful Sucker Punches rip holes in a lot of things, and fast resists are usually frail (eg Primeape). It helps to have a STAB which hits most of the tier's physical walls (predominantly Water- and/or Ground-type) hard. Entei and Espeon going makes it even easier for Cacturne to shine, too.
Exeggutor I'm going to miss if and when it goes up - it has bulk, hits so hard and if you can get it in your opponent is probably going to lose something. Its Psychic-typing lets it check the likes of Medicham, and Pursuit isn't too much of a problem either seeing as Skuntank is OHKOd by Specs Leaf Storm after Stealth Rock.