You have a bunch of pretty good ninjas, so here are a few teams you could try:

In my experience, Shizuka can be pretty nice as a kind of pseudo-SOSP because of her interruption mystery. If you go first (and they have less than 30 chakra) you'll interrupt and do a lot of damage; if you go second you're almost guaranteed to get her stage 2 (7 targets + interrupt) mystery. Even if they don't have less than 30 chakra and you move first, the her mystery removes super armor so you can chase ninjas who normally can't be (eg. EGF Kakuzu, Shark Kisame, Founder Madara) and the chase that follows will still immobile your primary target with Gaara's chase:

This team (and all following ones with him) does assume you have Gaara's L+2 and L-2 breakthroughs (the others are nice, but these are the primary ones you need. Tip: if you get his +2 or y+2 mystery, you can convert it to L+2 in the "select skill" part of the BT panel, and this will automatically give you the L-2 passive when you switch. They are paired so it's like 2 for 1). You want him as a support ninja who will create shields. Because Shizuka's attack and defense go up every time she's hit, she's also kind of like a budget Kushina in terms of scaling. So, you want her to survive a long time on the field so she can scale up and get really buffed. Gaara's shields will help her stay around longer.

Lightning main also helps her out, making her immune for 2 rounds and reducing her cooldown if her mystery kills a unit. Edo Itachi is a GREAT support, his mystery can help you shut down a lot of threats round 1, plus he has reflect like Kurenai and he also reduces incoming ninjutsu damage.

Overall I'd try this team first, unless you don't have Gaara's BTs or can't get them easily.

Here's a similar version of the same team but with Kushina. In my opinion, until you get Kushina to 4 stars and get her breakthroughs, the team with Shizuka would be better to use, but it's up to you and others might disagree. This basically as the same idea as the above team but just with even more shields. Again if you don't have Gaara's L+2 and L-2 BT maybe skip this, though you could also try it with 7 Swords Bee in place of Gaara. He will shield himself and Kashina at the start of the battle and then Earth Main will renew shields throughout. For that option you'd want to use 4 - 3 - 1 - 2 -3 for the talents and Chameleon as the summon.

You said you'd been using Shisui. Well, Shisui can be a support to Kushina and a secondary attacker on a team like this. Kind of like the teams above with some shields, but with a little more offensive presence in the early fight thanks to Shisui.

Another option using some of the ninjas talked about earlier. Shizuka and Shisui are the main attacking core of the team. Lightning main and Kurenai provide nice support with immunity, cooldown reduction, mirror reflect, and Kurenai's healing shield.

Hope this helps! Going forward I'd just suggest working towards Kushina's breakthroughs and Kazekage Gaara's too, if you don't have them already. But like I said you already have good ninjas with a lot of team options.