Like the title says, this is only my strategy and there are plenty of valid strategies under the sun. Also, it's ungodly long, sorry.

Despite the name, Easy Strong Approaching is pretty difficult since it's not just power or spam, it's combos/debuff clearing/stayin' alive (Uh-uh-uh-uh stayin' alive) too. But once you have the hang of it you win, mostly.

Alright, number 1. Go in with two teams. Not sure if this is something the developers purposefully did but in a two person challenge, Karin shows up in front of Hanzo, which is really, really good. The layout, for those who don't know, is:
Wave 1: three giants taking up three "team" spaces; like across from your entire team there's one; across from your
partner's team there's one; there's a third not directly across from either of you.
Wave 2: just Shizune.
Wave 3: Karin and behind her Hanzo in the middle row of the middle team slot.

Number 2: your team. I had Kabuto, Sakura, Hinata, fire main (if you're not fire main read as "other team"; I'm not able to help with earth, water, lightning or wind - well, I can if I look up their moves but I'm not writing a guide on them since I'm just not familiar.) and my layout was:

Kabuto x Hinata
x x x
Fire main Sakura x

and if it wasn't that it was really similar. (I've completed it with Kakashi, too, who's my combo-er but died waaay too fast.) My talents were:
1. Seal of Red Lotus 2. Feather Illusion 3. Celestial Prison 4. Genjitsu Mirror 5. Death Mirage 6. Summon: Gamachu (change if necessary)

The reason why all of this matters is: You need to keep everyone alive. Kabuto for his clones/heal, Hinata for combos, main for interrupt and debuff clear, Sakura for debuff clear and megaheal.

Number 3: The other team. I was with a lightning main so that's what I'll go by. Next time he's on and if anyone cares, I'll ask him about talents/formation. I think he had Sasuke/Hinata/Sakura. The point is Sakura's megaheal + killer combo starting with Sasuke's kirin. You'll be relying on this team for the combos. *ternative would be clone spam; say, a wind main with Sai.

Number 4: Wave 1, the poison giants. You'll sleep-chase the giant across from you and interrupt it. If your teammate can interrupt, let him/her take care of shimself with shis chase and use your Red Lotus seal on the one not directly across from anyone. Then take them out.

Number 5: Wave 2, Shizune, the Unfair Mario of Naruto Online. It's not worth it to go after her with the teams I suggested right away since... it's not enough time. With the Kakashi team I mentioned earlier, you'd have to wait a round anyway for cooldown, and with this one you need to build up the Kabuto power. The other team uses Sasuke's barrier, part 1 of his mystery, then it waits until he's able to use part 2. As soon as he's able to and a heal's not coming, go for it - trigger a combo - and let Kabuto and a Hinata's chase-triggered combo from you do the rest. The key is timing. You don't want your team using their chase opportunities before a heal and then not being able to use them after Hinata's chase. It may take a few tries, but you'll do it eventually. If the poison is ever too much, use Sakura's megaheal - but keep in mind that you'll want it later.

Number 6: Wave 3, Karin/Hanzo. Kill Karin by the mid-second round of this wave at the latest. Your taijutsu should be able to do this; target Hanzo with mysteries and begin wearing him away. At this rate Karin will get one poison spray in; DON'T bother interrupting it unless you're sure you can and you have another interrupter at the ready. Use Sakura's megaheal right after this, or if you used it earlier wait until you can. Hanzo will use his move, which by the way is awesome and makes me want him so bad (for my team, guys!), in the third round of this wave. First time he tries, INTERRUPT. With your sealing or the other team's whatever. But make sure it happens. Then beat him up for the remainder of that round and the next. After that, interrupt if possible (if you used fire main's move the first time and you don't have Neji, etc., you can't - no biggie. Kabuto and Sakura take your life high enough that you should be okay, maybe one person goes down) and spam jutsu again. Keep going until you beat him! Yay!

If you're frustrated because you're so close but so far, I have plenty of stories of this instance that will raise blood pressure. Don't give up! That's the ninja way!