List of weaknesses for my opinion:
Marine weak against: almost every units.
ok against : sphinx, scouts, and roman. But it take time for marine to reload rocket. Also when Roman come in number. Marine lost.
Chronite tanks weak against: all air units, hover tanks.
strong against: marine
Sniper weak against: phantoms, scouts if come in number, BQ, hover tanks, chronite tank if get close enough to shoot sniper.
strong against: sakatas aa only not land sakatas, chronict tanks if far range, marine.
Groditz weak against: BQ, hover tanks, and sniper if come in numbers.
strong against: phantoms, sphinx.
Hover tanks weak against: Saints, phantom.
strong against: all grounds units,especially aa sakatas, except if sphinx if fews hover tanks, and roman if a lot of roman and fews hover.
BLack Queen weak against: Of course weak against aa, sphinx. Other air unit can come in number to destroy BQ.
strong against: All ground units, except sphinx, and hover. Not a lot tho.
Roman weak against: BQ, Pride, gladiator, land sakatas.
strong against: the enemy base, and it have high health that it.
Scouts weak against: Of course aa, BQ if they come out in number, saint if come out in number too. Also gladiators. Sometime marine. And one more is sphinx.
strong against: All ground unit that can't fire air units. Except hover tanks.
Phantoms weak against: A bit of aa, cause phantoms can kill aa easy too except if there a lot of them at once then no. Weak against, BQ, saints, sphinx.
strong against: Not a lot just a bit effective on hover tanks. Then good effective against sniper, marine, and some chronite tanks.
Anti air sakatas weak against: Hover tanks, and sniper.
strong against: All air units, except phantoms if 1 aa at the time. Also it strong against missles. So let it guard your unit from missles or BQ.
Land Sakatas weak against: BQ, 1 strike they all gone( most of the time even special land sakatas.)
strong against: Hover if they come like 10 of them out. Strong against all land units. Including sphinx.
Gladiators weak against: Hover tanks, land sakatas.
strong against: Most air units.
NOw is to special units:
Special force weak against: BQ, and hover tanks.
strong against: rush the base and kills any unit fast except BQ.
Far snipers weak against: phantoms, BQ, saints, chronite tanks if have a chance, hover.
strong against: just shoot far range at land units.
Pride weak against: Hover tanks.
strong against: Air units, chronite tanks, roman, sniper, all unit have less health.
Now to hopital units:
Saints weak against: AA if come out a lot.
strong against: All ground units, except gladiator take times.
Sphinx weak against: All less health unit like marine, roman, land sakatas, special force,...
strong against: BQ, saints, scouts, phantoms, hover if come close enought, and all land unit if come close. Not the unit in front tho like marine no. It can kill marince but marine do more damage than it does.
Now talk about special genarator units:
Special sakatas weak against: Hover, BQ, saints, phantoms, and some sniper.
strong against all land units if few of them come out. Strong against enemy base.
That is all the units weaknesses and advantage that I can think of. Hope this help if you notice in the game. Good luck in the games ^_^