Oh, hmm. Yeah, I knew it needed a lot of changes but it just kind of worked for me. Maybe it was just my dumb luck (it happens a lot), but thanks for the suggestions and advice, it's really helpful. I might just scrap the entire thing and start over again with your suggestions in mind. Thanks, though.I don't think this is the topic for getting feedback on teams you're working on. That said... well, to be blunt, the team needs a lot of work. I don't have much time, so I'll just be quick.
For Rayquaza, if the goal is to take out opposing Ray, why Moonblast over Ice Beam? Also, why Earthquake over Precipice Blades, Thousand Arrows, or Thousand Waves? You also lack any sort of damage boost, so a wall can tank the set fairly well.
For Groudon... why Groudon? You're not using your STAB and I don't immediately detect any type synergy on your team with it. You're also not using your strongest attack stat At the very least, swap to Dialga or something. Also, Speed Boost + Quiver Dance is overkill. Switch to Tail Glow or change abilities.
For Arceus, it is a Normal-type without plate + Multitype. So, you are not Imposter proof. In fact, you are very Imposter-vulnerable because you have Spooky Judgement and they have Normal. So they're immune to yours and they hit you back with STAB.
For Shuckle... well, Shuckle is kinda bad as a wall. It was only decent Gen V with perma-Sand teams. I have no idea why you have both Acupressure and Agility. Scrap Agility for sure and consider a different boosting move. Acupressure is too slow and unreliable and liable to be stolen by Spectral Thief before you get anywhere.
For Lugia... that bird is a wall. Its offensive stats are too low to really use them for much, so consider at least switching to a support set or switching to a Pokemon with better offensive stats. Also consider Psystrike over Psychic. Aeroblast is cool, I like it, but Oblivion Wing may or may not suit your purposes better. I'm also not sure what your set intends to gain out of being an Illusion.
For Shedinja... see above about Agility + Acupressure. You're also quite vulnerable to pivoting moves, as a lot of players U-Turn on Shedinja to check for Illusion. Especially Shedinja leads. Sheddy can bluff Sturdy well, but Magic Bounce generally isn't the ability it wants to use to do it. Scrappy or Magic Guard are the usual best bets.
Honestly though, you're new so I'm not going to be too harsh, but I'm not sure how salvageable the team is without gutting most of it. It happens though, I have about ten or fifteen teams laying around I made that ended up being unworkable.