Congrats to your success, MostWanted!! Just like X5Dragon's team, you thrived with something less mainstream than Dual Screen Deoxys + 5 Set-Up Sweepers, so it's quite enlightening :d. Thanks for sharing your love!
I can see how Jirachi can be annoying without a really effective mon to absorb paralysis, and Fire Punch can put an end to Scizor. You can try Occa Berry on Scizor for this reason, and it also helps saves Scizor when it gets hit by a surprise HP Fire from Latios / Latias. Occa is cool, b/c people rely on HP Fire Latias / Latios / Celebi to break the Volt-Turn combination. With SR support and a taste of U-turn, they wont be around to stop Rotom-W :d.
However, I am pretty sure that you've tested Occa before, and end up preferring the 20% oomph of Iron Plate. In that case, the best thing you can do against Fire Punch Jirachi is let Rotom-W take the paralysis and weather Jirachi's hits. It sucks that you lose out on Rotom-W's revenge-killing prowess, but you still have plenty of priorities to go around. Also, Tricking Jirachi helps ALOT, because it can't paraflinch or pass Wishes in one sitting, making it MUCH less annoying, and may even be set-up bait for Scizor and Dragonite.
If Volcarona's a problem, you may possibly want to swap the roles between Dragonite and Terrakion - CB Dragonite & Double Dance or SubDance Terrakion. What this accomplishes, is that it provides Dragonite's ExtremeSpeed the power that it needs to check these threats much more easily. Since you seem to rely on Dragonite's ExtremeSpeed to check things, the CB boost may possibly help.
I understand that it's probably not the ideal switch. Terrakion is much more difficult to set up than Dragonite, and you just can't spam Dragonite's STAB move like you can spam Terrakion's STAB moves. CB ExtremeSpeed is useful, though, so it probably wont hurt to try (and to surprise people lol). CB Nite is fierce in its own right, dishing +1 hits from the get-go, so it is by no means shit.