Earthquake: Is Earthquake.
ThunderPunch/Dragon Pulse: Coverage.
Air Slash/Focus Blast: Coverage or STAB.
And Substitute+Roost is Great. Substitute Stops Damaging To Zard, and Roost Heals Up The Substitute Damage. If Zard has The Berry That Raises SA(Or Speed) when low in HP, this is even better, becuase Zard would use Substitute 3 Times For Protection and Berry Activation, then with boosted Stats, Roost Up(Roost only takes away the Flying Type For 1 Turn so its hard to predict roost and Hit Him with Earthquake) and with decent HP and Raised SA/Speed, He can Sweep Like Heck:)