To be honest, I don't think that Deoxys-D is the best fit for your team. Your team has a lot of issues stopping common spinners, especially Tentacruel, but also offensive Starmie in Rain. A lot of your Pokemon are very easy switch in opportunities for Tentacruel and not much on your team can OHKO it, and the Protect versions will just scout your Choiced Pokemon making it very easy to switch into. While Scizor can just Pursuit Starmie, the offensive variations in Rain will cleanly OHKO it with Hydro Pump, meaning that Scizor can't do its job, and foiling your plans. You say that when you see your opponent has a spinner, you just don't send Deoxys-D in, but that's not how Deoxys-D is meant to be played. It's not really an effective Pokemon outside of the very few first turns of the battle. There are other good offensive leads that will be effective even if the opponent has a spinner, because they can put a lot of offensive pressure as well as setting up Stealth Rock. Garchomp and Terrakion are the best, and I think that Garchomp would be an excellent fit for your team. It can set up Stealth Rock and immediately put pressure on the opponent with its STABs. You already have a spinner so I don't think Terrakion's ability to stop other SR leads would be that useful, although you may want to try it too.
There are also some threats that could really do a lot of damage to your team. The main ones I see are offensive Water types powered up by Rain, and the second is Rock Polish Landorus-I. Landorus-I can easily set up on Jolteon locked into an Electric move, and then proceed to sweep your team cleanly using a combination of Earth Power and Hidden Power Ice. Whenever Landorus manages to get a boost, your chances to lose immediately are very high, barring something like a Bullet Punch crit. As for the Water types, both of your Water resists are extremely frail and will take a ridiculous amount of damage from boosted Water moves, meaning that you will often lose a Pokemon when they switch in. Honestly, I don't think Darmanitan is a very good Pokemon for your team. Since you carry no weather, every time the opponent brings Rain, Darmanitan will be fairly useless. It's also weak to Stealth Rock and part of your Voltturn chain so you will have to lose momentum very often, going to Starmie spinning the rocks away, for Darmanitan to even work. It's going to take a lot of residual damage which is fairly bad with all the priority in the metagame nowadays. I think that you could replace it with a Latios. You don't need all of your Pokemon to be part of your Voltturn chain, 2 is usually enough if your Pokemon are strong enough. Latios is able to take Water hits moderately well and heal back the damage with Recover, as well as being an alright check to Landorus-I. Since this is an offensive team, I think that simply checking those threats will be fine and Latios does that all right, while also having devastating power, fitting the offensive spirit pretty well.
Here are the sets you should use:
Garchomp and Latios
@ Focus Sash
EVs: 4 HP / 252 Atk / 252 Spe
@ Life Orb
EVs: 4 HP / 252 SpA / 252 Spe