well you said ultimate defence so this must be in the desert.
gaara can handle virtually anything they throw at him. only things he cant beat are probably visual genjutsu, raikage level speed and hax attacks like jinton. other than that, gaaras fuking unstoppable.
tsunade cant defeat 4th kazekage, try as she might. he reacted to and defended against gaara's attacks even when he was firing missiles down from above. no sannin can do that. they are doomed to get hit no matter what they do. if the attack from above fails, theyll still have their legs and lower body trapped in sand.
sand clones are THE best clones in the series. they dont disappear or disperse when damaged, they just become weapons again.
oro's summons are sand crushed virtually instantly. manda is sucked underground if need be. think about it. his main attack is going underground to attack from behind.
anyway since his dad handles tsunade quickly enough, he can go help gaara fight off jiraiya. jiraiyas best chance at beating gaara is oil and i dunno if gamabunta will last that long vs sand ocean.
oro is sealed by the pyramid. he isnt breaking out of that. he has no jouki boi or meteors. jiraiyas katons might melt the gold which isnt a very good idea.
oh god i forgot third kazekages in this. this makes it even more of a stomp because he can fight against jiraiya while gaara handles orochimaru. and if your saying "kuchiyose edo tensei" he needs to summon them first. bit hard when your fighting sand attacking you from every direction. furthermore, gaara can seal them or bury them. your choice.
I also think the needle Senbon jutsu may be too fast for Gaara's sand to react to.
so what if it is? he has armour.
She can tank the damage she receives in the fight
world method will still impale her skull if first restrained by the iron sand on the ground
