Rayquaza Team

Strong enough for... a duo? Yeah that should be fine, but I'd use GoBattleSim to confirm.
Strong enough to guarantee three damage balls? Depends on how competitive your friends are.
As far as replacements, your team looks solid enough that I honestly wonder if this is just a weird flex, but the only thing on that replacement list that's really making your team all that much better is charge TM'ing that Mamoswine into Avalanche. Nothing else is going to significantly help your DPS situation, aside from maybe slotting in that jynx over the dragonite.

Tl;Dr: Use GoBattleSim and figure out if your team can duo RayQ. I suspect it can. If not, getting AV on that mamoswine is your next best include.

Nice team you have there. Three Mamos should be enough for taking down Rayquaza. Just be mindful if Ray is packing Outrage. Your team is fine, unless you're looking for more DPS. For a duo raid you'll be set.

This is my team, I'm planning on Duo it:

Lv 40 Mamoswine 98% (15/14/15) PS/AV
Lv 40 Mamoswine 96% (15/15/13) PS/AV
Lv 40 Mamoswine 96% (14/14/15) PS/AV
Lv 40 Mamoswine 91% (14/14/13) PS/AV
Lv 40 Weavile 98% (15/15/14) IS/FP/AV
Lv 40 Weavile 91% (15/15/11) IS/FP/AV

While my brother has a 100% Jynx, two Mamos, a Weavile and a couple of dragons.

Why using dragons over ice-attackers? According to pokebattler, lapras, cloyster, articuno... have better DPS and TDO than dragons in most scenarios.