darkSpyro

...I mean, I have no idea if the dev team for Battlecast takes suggestions unlike the others, or if they can even listen to them, but hoping it's a yes since it's a competitive-driven game. Even if it's not possible or not allowed,at least it should make for good discussion.

So, Lair of Kaos plays on all final bosses of each Area. While it's a great theme by itself, it's slightly quiet for some bosses which can get quite hectic, and a big thing about the Doom Raiders as well is that in their game the leitmotifs were a big thing. My suggestion is, if possible, I don't know how using existing Skylanders songs for the game works and if it even works that way, is having different themes for each, of course adjusted since some aren't actually going to work for 3-6 minute battles.
I'm getting them all off of the music rip channels on Youtube since there's not even a fifth of the actual series soundtrack in the Official Soundtrack CDs.

• Dreamcatcher - While her soundtrack theme is too slow and her boss and villain themes are too fast and would get old fast, the tempo in the Fight music for Telescope Towers is just right.
  
• Chompy Mage - Both of his themes work(they're not even his,they're both remixes of existing songs) but I think the Trap Team version sounds a lot more fitting to the Life Realm.
  
• Wolfgang - All of his themes are incredibly fast and the dubstep would get in the way of the theme, which is understandable because of the Trap Team level he is in and how the battle itself was a rush. Not only Superchargers has the perfect replacement with Brimstone and Boulders, it's even used in his Boss Pursuit level.
  
• Golden Queen - Both her themes work, but Part 2 has a better loop.
  
• Chef Pepper Jack - He has the same issue as Wolfgang of a fast paced debut battle, but I actually think his first theme(not the villain theme version)has just the right pace and tempo.
  
• Chill Bill - Things start getting a bit difficult here. He's not a major boss battle and his villain theme is just loud and short. Though the Water Realm songs actually fit nicely, there's Frozen Fossil Festival that sounds particularily icy just for him.
  
• Pain-Yatta - Also took a bit of creativity. The After Party does fit his theme and all, but it also sounds a bit similar to Chef Pepper Jack's theme and is really fast paced. There's Wilikin Workshop Fight 1, which is slower paced but fits the Realm theme with the instruments a bit better.
  
• Dr Krankcase - His own ingame boss battle theme(part 3) is a remix, but hey, it works.
  

Stretching my luck here a bit, but I also thought of some that could also work for the midbosses. You do fight them twice unlike the main bosses,and as commented on the Life Realm update Broccoli Guy is even more intimidating than Chompy Mage with his tatics.

• Buzzer Beak - Thinking of a theme for him actually inspired me to make this suggestion! Phoenix Sanctuary's Arena Theme fits nicely.
  
• Broccoli Guy - Most of Life-y level themes fit there, but not as much as in a jungle and have a good pace at the same time, an exception is Know-It-All Island Fight 2.
  
• Count Moneybone - Nothing more glorious than Moneyback Guarantee itself. I would suggest the original Swap Force 3DS final boss themes because they have a better Undead feel, but they're just so short and the only source is in Soundcloud with all exclusive songs(including Party Town and Margaret's theme) together - who knows if Acti even has those still.
  
• Grave Clobber - My favorite theme from Golden Desert is the Chompy Worm theme, but not that or the Arena theme fit him, The Golden Desert Fight 1 does.
  
• Grinnade - Anything with as much beeping as his theme would get old fast. Lost City of Arkus Fight Theme, however, keeps his theme and fits like a glove.
  
• Captain Dreadbeard - Isn't the best Cutthroat Carnival song on the Water Realm rotation already? Can't get any better for him than that. However, if it was needed to have another one, I'd say Rainfish Riviera's Fight Theme but I can't remember if that *also* isn't in rotation.
  
• Bomb Shell - I've never seen anything really magical about Bomb Shell's gameplay, which is unfortunate since no whimsical-sound themes fit then. His fighting style strongly reminds me of Vault of the Ancients Vehicle Arena, which is close enough to a magical area.
  
• Shrednaught - Their theme is DEFINATELY too fast paced for something that easily can go over 6 minutes. Something mechanical-sounding that's really close though is Secret Sewers of Supreme Stink's Fight 1.
  

So woo huge post. I'm alright if this can't be done, it's just something I thought about a lot and decided to share even if it's just for discussion. As in, if other users have better ideas, feel free to chime in too! I'm not familiar with Swap Force's soundtrack for example so who knows,maybe there's something more fitting for a character there.

I suggest Frostfest Mountains - Fight 5 for Chill Bill. I'll give more ideas later when I have more time to think about it.

Yeah, that one actually feels like a fight, especially since Chill Bill's gimmick ought to slow down a game.

I agree with most of your ideas, here's a few more. I find it easier to assign a Villain to a theme rather than assigning a theme to a Villain:

Land of the Undead - Fight 2 for Count Moneybone
Captain Bristlestache/Blubberbeard Battle for Captain Dreadbeard
Spellslamzer - Part 1 or Luminous Boss Battle for Dreamcatcher
Cluck Chicken HQ - Fight for Grinnade
Monstrous Isles - Pterashark Battle for Bomb Shell
Ridepocalypse - Turbo Teeth Battle for Golden Queen
Kaos Mode - Wave 1-20 Fight for Grave Clobber
Know-It-All Island - Fight 1 or Fight 2 for Buzzer Beak
Chez Zeppelin - Fight for Chef Pepper Jack
Evilized Glumshanks - Part 1 for Dr. Krankcase
Sheep Mage Battle for Chompy Mage

I remember looking up a few of these songs but choose otherwise since their loops are just too short. It worked in their occasions since the battles are pretty short but could get old in a slow paced card game.
Turbo Teeth's theme is just Golden Temple though, and both are some really obscure theme from SSA, which I never thought fit any of those occasions :U

The first Kaos Mode theme and Spellslamzer's theme definately work for the situations though. Kinda wish Spellslamzer was the boss in the Magic Realm but I guess he was too much of a spoiler to be considered at that point.

I haven't watched a lot of Battlecast gameplay so it's a bit hard to guess if the theme I suggested would fit with the themes used before the boss themselves and if they fit with the pacing of the battles. But if you say Kaos Mode theme fits, I somewhat get the idea. What themes are used during the game? Mostly from Trap Team? Or they come from multiple games?

Mostly SSA and Giants as used,good choices though.

Jasoninquires had the majority of the Fire Realm recorded in his showcase video here:



Chef Pepperjack at 50:59. There are other videos with Water Realm content and PVP really likes to roll Undead Realm as background,but other than small parts from JJAtelier's videos I haven't seen anything from the other islands in terms of soundtrack.
Battles are medium paced since you do have to plan strategies and whatnot, and the AI is fast to pick but likes to play as many cards as it possibly can in a turn. Pretty much why calmer-but-still-action tracks play such as Stormy Stronghold and Crystal Eye Castle play, but nothing with small loops. Weirdly enough I DID see Stormy Stronghold play here at some point but in this video just the latter shows up.

Keep in mind this video is a slightly older update, so some themes might've moved out to other Realms,others added for variety.

Small bump now that Kaos' island is at the corner. Makes one wonder,is it really a matter of just Lair of Kaos?
Here are my suggestions for the area now that we know what it looks like:

Regular Battle - Super Evil Kaos Final Phase - The song actually is The Necropolis from SSA,but there isn't any video with that version. Slow,intense, perfect for an evil lair. If that's not enough,however:
The Ancient Plans - Even slower pace, even more bleak and villainous. Feels more like climbing a fortress which is this island's appearance.

Kaos - SSA Boss Battle is a no brainer(no video with just the song, this being from the devs it's an official version). Very long for a possibly long battle, worthy of a final encounter. Better than the SC or Traptanium Kaos themes,which are too slow and too fast respectively.
Robo-Kaos Phase 1 is an amazing mix of Lair of Kaos and Bringing Order to Kaos. The mechanical noises are a bit repetitive,but depending if he's going in alone or with some help it could very well fit.