Garra and Sasori win high difficulty.
1) both Garra and Sasori have the ability to penetrate their opponent, leaving them immobile. So, seeing as the Hachi already has openings in its tentacles, all either has to do is create a large enough tsunami that swipes against them.
2) 1 tails has futon jutsu, which is electric elements weakness. This can potentially eliminate Ay's raiton armor. It's size is great enough to cover large scales, so it wouldn't be a matter of being able to catch Ay, but rather covering enough land so he wouldn't be able to escape.
3) Garra's sand has already displayed the ability to withstand Ay's armored strikes. This shield isn't chidori with its piercing effect. So both Sasori and Garra could use defenses to defend against Ay.
4) TBB denotes upon impact, especially if it collides with an opposing force, weaker or not. Futon bullets could be used simultaneously to counter multiple TBB being fired, along with sand shields IF needed.
Ultimately, Bee would be more vulnerable to poison using Hachi. Its size would be an easy target.
Garra is the most technical than all those involved, whether it's his sealing, body-flicker, use of clones, flight, or third eye.