well itachis usual style is clone feint + basic genjutsu. gaara can kai out and genjutsu doesnt work on sasori period. kimimaro can take on and tank 100 puppets. fairly easy to draw a scratch from kisame with iron sand however. his usual fighting style is combining samehada with brute force taijutsu. a terrible fighting style to fight these three with. their best chance at dealing with itachi is a gigantic magnetite/gold/sand tsunami flowing along the ground. if yondys defeated, gaara can pick up and control his gold. its just a matter of getting it out there before itachi paralyses them both. once they do they should have no problem restraining itachi and pulling him down. gaara then sinks him.
samehada's hilt is metal. meaning he gets attracted to yondys gold dust magnet style.
itachi likes kunais and shurikens so he will be wtf'ing at them not even working for him. while thats happening gaara performs the capture. remember he can fly and rain down sand hail as a distraction as well. sasori does iron sand world method and finishes kisame. kimimaro gets trapped by magnetite too eventually.
only way itachi can win with no knowledge is a quick genjutsu blitz