I'm pretty sure a kunai would blow it up.true but deidara's bombs are guided. His bombs dont blow up unless he want them to.
If not that then Gamabunta or Gamaken or really any of the toads could do it for him. Remember that toads have elemental jutsus too.
Bunta uses water/oil( to strengthen fire attacks)
Gamakichi uses fire if I am not mistaken
Gamatatsu uses water
anyway they have long distance attacks they can use. As does Minato. I know we have only seen him using FTG and rasengan but honestly does anyone really think that those are all he had? He had one unknown element (probably wind) mastered, because he was planning on combining it with the rasengan.
He doubtless knew all of the lame jutsu that fodder ninja use, because well he would be a poor excuse for a kage if he didn't know jutsu that fodder nin and genin know.