Assault units work fine against Stingers, although you may take losses. Immediately supporting your assaults with high-DPS units means that most porc will go down without too much casualties.
This is the most basic way to attack porc, although it is unadvisable to use this strategy at high porc densities, such as multiple Desolators or that Doomsday cannon (forgot the name of he heatray-plasma turret)
I.e Using Halberds to push into Stinger, while Bolas/Dagger/Mace follow up and destroy everything.
Rover equivalent (I think?) is Ravager + Scorcher + Fencer.
Spiders can use Hermit + Venom + Recluse.
Heavy Tanks can use Minotaur/Cyclops + Ogre/Blitz.
Cloaks can use Knight + Glaive.
Softening it up with artillery is advisable.
Key point - try not losing non-assault units while rushing porc. Most assault units cannot effectively hit other units, so they tend to be not as useful when fighting against another army, but losing riots can lead to getting swarmed, losing raiders mean DPS is lost, and losing skirmishers, depending on the factory's need for them, can be crippling.
Of course, if your assault unit is the type that consistently hits other units (Grizzly, Cyclops etc), try not losing them either.
If you get massive porc, such as in big teamgames, it might just be best to get a superweapon.