if you get a decent heavy repeater for canderous he is excellent for ranged support, i went through the star forge with him and bastila went i went ds and he often remained standing even if bastila and i fell - give him decent armour etc. and max out his toughness, implants, one of his long ranged feats, and his heavy blaster feats, plus his conditioning feats and he is near untouchable.
as for hk, i always equipped him with zaalbar's bowcaster and that seemed to work well with him. again he is great for ranged support as you can get his defense really high with armour plating.
for carth, i liked using double blasters and chose his feats to make him a very effective ranged attacker too.
the rest i never really used so can't help you there, apart from all the jedi had lightsabers of course
