Units in PvT
Vults
Goons/Obs is the best way to deal with Vultures and their Mines.
Tanks
SpeedZeals and DTs are best against Tanks. Running SpeedZeals to Tanks in Siege Mode is the best way to force Tanks to fire on each other, as Tanks have a minimum range. Storm can be used to weaken Tanks that are placed close together, and DTs can be used to get free kills if your opponent lacks Turrets or enough energy to Scan the vicinity.
Tanks/Vults
You want to meet this a force of Goons/Zeals. Run the SpeedZeals to the Tanks, cause friendly-fire between Tanks, and possibly dragging Mines to the Tanks. Let the Goons deal with Mines and Vults.
Tanks/Gols
You want SpeedZeals for the Tanks, and Temps to Storm the Goliaths. Mix in a few Goons as you see fit to provide ranged-fire support.
M&M
Goons/Zeals/Temps are best when fighting an opponent using M&M. Storming M&M will reduce the enemy units to puddles of blood. Reavers also work, but Reavers can easily be out-microed by a good M&M user.
M&MF
You deal with M&MF the same as with M&M, except without Zeals. Just use Goons/Temps to storm the Rines, and try to kills the Bats before they get to your Goons to deal splash damage.
Ghosts
You will need Obs for cloaked Ghosts, and just use Zeals/Goons to kill the Ghosts themselves.
Wraiths
You need Obs for cloaked Wraiths the same as with Ghosts, and use Goons to kill them. you could also use Sairs, but they lack other practical uses in PvT unless you plan to use DWeb.
Valkyries
You probably won't encounter Valks, but in case you do, Carriers will do just fine against them unless they have a large number of Valks, so using Goons will suffice.
Battlecruisers
Battlecruisers can be dealt with using Storm, Goons, Scouts, Carriers, DAs...the list goes on. The best way to deal with them is to use Storm with Goons or Carriers. Other units lack practical seconday uses.
Science Vessels
Feedback works here well, if you can cast it before they run the Vessel away. Otherwise just try to kill them before they can do much damage to your shields/energy using EMP.
~*rpf