Amaterasu and Yamaraja's debuffs are both B-'frame'/'class'/'type'. (terminology comes from google translate of jp wiki)
Same frame = no stacking. Different frame = yes stacking.
Moreover, Yamaraja's debuff is weaker than Amaterasu's. So, Amaterasu's presence automatically strikes out Yamaraja, more or less.

Raguel's atk debuff is A-frame; -15%. I think that she's worth including the team, unless you're using Joan of Arc, or setting her atk debuff as your ex skill, as that is A-frame -20%. That said, maybe you hit hard enough to be confident in not needing more atk debuffing.

With water, it's hard to mess up. Throw Snow Raphael, Cthulhu, Ryu-oh, Aphrodite, Poseidon, Belphegor, and Triton into a bag, then draw 4. End result will vary from better-than-Thunder to great. Water's that loaded.
Since water has so many options, instead of suggesting a party, I'll just offer notes on each one, then you can pick according to taste and/or situation.

Snow Raphael - B-frame -15% atk/def debuff. General purpose 30% damage cut. Orb removal.

Ea - her main thing is having a maximal damage against stunned enemies buff. Gets awakening in 5 months. The maximal damage buff is actually very potent (and finicky), but since she doesn't really offer anything else, you want to sort out all your non-damage needs first. Most people don't have the selection to work with to make Ea a good choice for the final slot, but you actually do. It's something to think about.

Cthulhu - Orb removal (higher cooldown than Snow Raph). C-frame -20% def debuff (highly valued). A-frame -15% atk debuff that also attempts to dazzle.

Ryu-Oh - A-frame -20% atk debuff. A-frame -20% def debuff. Overdrive extension.

Aphrodite - Healing. Debuff removal. Triple attack buff.

Poseidon - A-frame -20% atk debuff. Debuff blocker/35% fire resist buff. Damage cut and element resist buffs do stack additively, btw.

Shiva - uhh.... as basic an attacker an SSR can get. I'd say that she's an example of one who was ok at launch, but has grown obsolete in design over time. She has no place in a party when everybody above is available.

Cupid - can attempt to inflict dazzle. 30% fire resist buff (her main draw IMO). Element resist buffs cast by kamihime do not stack with each other. Probably not making it into your party, outside of some very specific plans.

Belphegor - 30% current rage gauge reduction (this is good, but remember that it's based off the current amount of rage gauge left). Stun extender. B-frame -12% atk/def debuff. The rage gauge reduction is why I'd include her in the bag above.

Gabriel - A-frame -12% atk debuff. B-frame atk/def buff. Small burst gauge rate increase buff. If you're like me and have 0 water SSRs, Gabriel's perfectly usable. With what you have to work with, don't even think about Gabriel.

Oceanus - her main thing is having a maximal damage against stunned enemies buff. You have Ea. Pass on Oceanus.

Triton - combo atk debuff (far better than it initially appears). A-frame -15% atk debuff. Self heal/buff. So, that combo attack debuff? It doesn't sound all that great. When I rolled specifically for Triton, I was aiming for the atk debuff. I got her, and she's a mainstay in my team. When that combo atk debuff is active, I've never seen a double or triple attack. That's the main reason I include her in the bag.

Kikuri-hime - +15 burst gauge to the party. That can be either 'solid' or 'the last piece of the puzzle'. If you're using Shingen as your soul, Kikuri-hime in your 5th slot will be the finishing touch. She'll help guarantee that Shingen can burst along with everybody else. If you're not using Shingen, then Kikuri-hime has no shot in making it into the team of SSRs. She doesn't make it into the bag because of that reliance on a specific strategy.

Enkidu - even without SSRs, she'd be just filler waiting to be replaced. With what you have? She gets skipped over automatically.