Recapping the idea on Fierce Diety, and other LoZ (Legend of Zelda) characters; From the Majora's Mask, as of the mask transformations, you'd have to add EVERY mask, for fairness, and that would be a heck lot of work, yet a heck lot of fun. Imagine, turning into a Giant Link. You'd have to be a LOT smaller than the one in LoZ: MM, but you could still be about 5x the size of your normal character if you actually GOT it, being that it would be rare. The other masks, being less useful, would be added in too. Sort of like Goldeen in the Pokéballs. You need something to make up for those powerful chances you get. For a full capping of this, instead of a recap, I'll post a mask list, with my comments on how you'd get a change. For using the masks, you'd have every other move the same, but like on Kirby, you'd get your B changed (That is, saying that you use the default controls on the GCN controller). Here it is, but please remember, young link only!:
1. Deku Mask: Link begins the game with this mask. As the Deku Shrub, he can hop on top of water a couple times, as well as shoot bubbles at enemies. Also, the Deku Shrub can burrow into flowers and then shoot into the air – gliding down slowly. Controls: A: Spin B: Shoot bubble ((What else? You get to shoot bubbles as a deku with a little green cap on!))
2. Bremen Mask: Link receives this mask from the weird guy in the Laundy Pool area of Clock town at night during the first or second days. It is used to herd chicks in the ranch, which will get you the Bunny Hood. ((Make a stampede of chicks run across the map, falling down from the sky a bit behind you, then running forward at full speed, until they either fall off a cliff or walk out the edge! Similar to Marill or whatever that Pokémon's name is.))
3. Great Fairy Mask: You get this mask by returning the second lost fairy to the Great Fairy. It can attract Stray Fairies in dungeons. ((Same as grabbing a Maximum Tomato - Not a Piece of Heart. Heals a bit.))
4. Bunny Hood: When wearing this mask, Link runs at an increased rate. You get it by using the Bremen Mask and herding all the chicks in the Chicken Coop of the ranch during the day. ((Ummm.. Duh? Limited-time free Bunny Hood.))
5. Mask of Scents: Follow the Deku through the tunnel (use the Bunny Hood to keep up) that is to the left of the Deku Palace. The mask can detect scents such as mushrooms. ((Hmm... Tricky. Probably let you pull a random item out from the ground? Don't know. Open to suggestion.))
6. Goron Mask: Play the Song of Healing for the old Goron ghost after following him to the Goron Shrine. The mask turns Link into a Goron, complete with increased size and strength. Controls: A: Curl (hold down A, and then press up to build speed) B: Attack If you hold down A and then press B, you will do the Goron Stomp. ((Again; what else? Changes you into Goron Link with the green cap! Lets you do a roll, like Jigglypuff's in Melee.))
7. Romani's Mask: Complete both Romani's and Cremia's notebook entries. This mask gives you access to the Milk Bar in Clock Town. ((Lets you drink a bottle of milk. Like his taunt, but heals a little.))
8. Kamaro's Mask: Play the song of healing for the guy dancing on top of the mushroom to the north of Clock Town. He is only there at night, and the mask allows you to dance. ((Lets you dance around, which deals damage to nearby enemies! Hi-ya! Karate Chop!))
9. Blast Mask: Stop the thief after midnight during the first day in North Clock Town. You can blow up objects using this mask – just like a bomb, but you will loose one heart per blast. ((Duh! You take 50% damage to blow up, and hurt nearby enemies with a big bang! Ka-BOOM!))
10. Kafei's Mask: Speak to the woman in the Mayor's House in East Clock Town. Used in a couple notebook quests. ((I forget what the heck this mask was. Add it in as a useless one for looks, like Goldeen was.
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11. Captain's Hat: Defeat the sleeping skeleton in the graveyard. The Hat allows you to speak to the undead. ((Duh? Call up a few Redead friends. Note: They're NOT friends, they'll latch on to you aswell! Sound fun? =D))
12. Mask of Truth: Complete the first Spider Dungeon. It allows you to speak to the weird stones around the world. ((Another useless one, being that it can't really have a use in Brawl.))
13. All Night Mask: Stop the thief on Day 1, then buy it for 500 Rupees from the curiosity shop on Day 3. It allows you to stay up late and listen to the old lady's stories in the inn. ((Yet another useless one.. Actually. Scrap that. Keeps you immune from one shield break as long as it's worn.))
14. Stone Maske: Use the Lens of Truth near the entrance to the graveyard to find a soldier. Give him a red potion to get the mask. Some enemies will not notice you while wearing this mask. ((Like it says, some enemies will not notice you while wearing this mask. It's like the Cloaking Device from Melee.))
15. Keaton Mask: Go to Kafei's house in the afternoon of the third day after you take the pendant to Anju. Wear this mask and slash at the bushes that move (like the ones in North Clock Town) to make Keaton appear. Answer his quiz questions correctly to get a Heart Piece. ((Yet another one, merely for looks in the game. Can't have everything you want, now can you?))
16. Don Gero's Mask: Light all the torches in the Goron Village, then use the Goron roll to destroy the barrels on the chandelier. Take the chunk of meat to the shivering Goron in the mountain village. The mask will allow you to speak to frogs. See the Frog Locations below. ((Lets you ribbit, which will knock enemies back with a scary, yet weak stun! Ph34r t3h m45k!))
17. Zora Mask: Push the sick Zora to the shore in the Great Bay, and then play the song of healing for it. The mask turns Link into a Zora. Controls: A: Swim B: Dive R: Energy Field ((Aye, for those fans of whatever his name was.. I forgot it again.. Here you are! Fire those Zora Boomerangs at your foes, and make them know what pain REALLY is! Dang! Now they smell like fish!))
18. Garo's Mask: Ride Epona into the racetrack on Milk Road, and win the race to get this mask. This allows you to get into the Canyon area. ((Another useless one, for looks. Like Goldeen, it's just that you have more of these than Goldeen.))
19. Postman's Hat: Can be used to open mail boxes in Clock Town. You get his mask by going through the Kafei notebook entry until you get the letter to Aroma. Give it to the postman, and then talk to him about it. ((You get to pull out a letter, and toss it like a boomerang at enemies! Watch out for paper cuts!))
20. Circus Leader's Mask: Go into the Milk Bar, and help the Zora with his sound check by playing the instruments while wearing each of your three transformation masks (Deku, Goron, Zora) and as Link. If you wear the mask during Cremia's notebook entry there will be no attackers. ((Another useless mask. But it does look good!))
21. Couple's Mask: Complete Anju's notebook entry by recovering the stolen mask. Wear this and speak to the Mayor after 10pm for a heart piece. ((Hm... Use it at the right area on the right map, and you get a heart piece? Otherwise, completely useless, I would guess..))
22. Gibo Mask: Play the song of healing for the mummy in the Canyon house to get this mask that will allow you to speak to Gibdos. ((Speak to Gibdos? How about 'HEY!! GIBDOS!! COME HELP ME!!' - AKA: Call a few Gibdos to come running and latch on to ANYONE - including YOU - that they run into!))
23. Giant's Mask: Kill the Eyegore in the Inverted Stone Tower. This mask makes Link big. ((Duh! Makes you 5X size for the time wearing a mask lasts! And gives you a few power boosts!))
24. Fierce Diety Mask: First gather all of the other masks in this list. Then, complete the mini-dungeons at the end of the game, and you will get this mask. It turns link into Oni Link. ((Yes!!! I really like this mask!! Removes the shield from link, just basically again TRANSFORMING him, 'DUH?' into Oni Link. Fierce Diety means Fierce God. He's a WHOOPER! Replace 'B' move with swinging your sword and shooting an energy disc. Fierce Diety for the win! And as of the 'What!? No shield!? That's BULL!' - Who never heard of Parrying?))
Well, that ends that. As of the specs, I think masks should last both till they've been used with B - if they have a use - or 15 seconds. Some will be used automatically. You'll see him pull out a random mask, put it on, and something will happen, then he'll take it off.
Well, what input do you have?
Looks like Serene Shadow 
uber suggestion, dawg! Comments? Bring it u LOZ haters!
