darkSpyro

• A new story: the Skylanders travel back in time
  
• Set in a completely new region, the Vile Wonderlands, with an all new cast of NPCs: Flux the Archivist, Furcifer the Seeker, and more
  
• Each Skylander gets to travel to their own past to play in a new level
  
• Levels are more deeply developed- fleshed out with NPCs to talk to, side quests, take more than a few minutes to finish (Plus you can choose to go back to the main hub, "Homeworld", or straight to the next level)
  
• Also, the hub world is expanded- Some Soul Gems are hidden here as well as new "Quills" that unlock art and videos (not trailer videos)
  
• Better character development
  
• Heroic Challenges are KAPUT and come as standard stats (the Skylanders have been training after Giants)
  
• 3DS version gets more unlockables in level branches but still retain a linear path you can follow if you want to
  
• Also on 3DS: new hidden paths to best your times, online time records, StreetPass compatibility, bonuses for "Running" in a level, exclusive rewards for clocking times
  
• Also on 3DS: For those who aren't fond on time records- new types of levels apart from Radience Challenges and Platforming Challenges, more unlockables again, hidden levels, extra hub worlds, secret abilities to earn out of leveling up
  
• Also on 3DS: A Button now switches Skylanders and D-Pad rotates the camera (in a manner similar to Super Mario Galaxy)
  

Sandrose
"Every rose has its thorn!"
An awesome female Horned Dragon decked out in deadly spikes.

A Attack: Crush- Stomp your feet in one spot(with mid range splash damage). Can turn around while using even though stuck in spot.
B Attack: Gulp- Hold up your throat to block amounts of incoming damage(functions like 's shield but better).
Z Attack: Rip- Shoot out homing spikes from your back.

Personal note: If you do not see the reference you need to play the original Spyro games again. ;

Scarrvy
See the contest topic in the Giants Forum.

Waxhead
See the contest topic in the Giants Forum.

Magnetzium
"I know I'm attractive!"
A sleek feminine robot with copper, silver and blue metal body components.

A Attack: Deal damage by jetting forward in a manner like the Afterburners (Holds as long as you keep on the button)
B Attack: A somewhat complex to explain attack. As long as you hold the button, you will send out projectiles from the sky to damage your opponent(automatically aims, like Rain of Skulls but continuous, faster and weaker). The tricky part is as long as you hold it you're in place, but you can use your control stick to set a spot to teleport to when you're finished attacking. The spot you are moving to is marked by an ever so faint orange glow.
Z Attack: Sets a Magnet Bomb on the ground that sucks in enemies and explodes to deal damage.

Personal note: Yes, this was inspired by an idea I saw when I was stalking the Giants Forum.

New Undead Skylander- Gripper
[no catchphrase yet]
A grim reaper.

A Attack: Attacks with scythe.
B Attack: Shoots a continuous "strafing" beam similar to .
Z Attack: Outlands Vortex that sucks in enemies and deals continuous damage.

Every character is available from Wave One but become more common at certain times and others rarer at certain times:
Old characters remain neutrally available through all months but the last
First month of release: New Magic Skylander (Uncommon wide-release variant- Amethyst Magic character)
Month two:
+Sandrose (Uncommon wide-release variant- Topaz Sandrose)
-Magnetzium
Month three:
+Scarrvy (Uncommon wide-release variant- Fluorite Scarrvy)
-Waxhead
Month Four:
+Waxhead (Uncommon wide-release variant- Ruby Waxhead)
-New Air Giant
Month Five:
+Magnetzium (Uncommon wide-release variant- Copper Magnetzium)
-New Magic Skylander
Month Six:
+Gripper (Uncommon wide-release variant- Stone Gripper)
-New Life Character
Month Seven:
+New Air Character (Uncommon wide-release variant- Diamond Air character)
-Sandrose
Month Eight:
+New Life character (Uncommon wide-release variant- Emerald Life character)
-Scarrvy

Next few months:
Variants are all available at once, but rare, and all characters are generally available.

Month before next game's release:
All new characters and their variants become more common but old characters become less common.

Hopefully this schedule allows both collectors to stay interested in variant releases and people who just want to grab everything to do so.