When you say "they" who are you referring to?
Anyways, you're right about Gliscor. Here is a calc of 252 Atk + nature Scrafty Ice Punch on 252 HP Gliscor:
252Atk Scrafty (+Atk) Ice Punch in Sun vs 252HP/0Def Gliscor (Neutral): 65% - 77% (232 - 276 HP). Guaranteed 2HKO.
Gliscor does 77-91% in return, but clearly that's more manageable.
Weavile, however, does OHKO all the time with Ice Punch. Which brings us back to "Weavile is a threat."
So if we're building a Sun Team, we've got Ninetales, Leafeon, Gliscor, Conkeldurr (to take out Weavile and Tyranitar). What's left? Something to take opposing Heat Waves and stop Trick Room. I nominate Chandelure! And that leaves us with needing another water and ground resist, and I nominate Virizion! How I feel we're Flygon and Haxorus weak, but hey, who wants to test this team out?