[spoiler=Sound]
Concept:
The Sound type is embodied by battle moves which make use of soundwaves, and Pokemon who specialize in the usage of such moves, e.g. Loudred and its booming voice, or Chatot with its voice mimicry. In general, these moves are more effective through dense mediums which allow sound waves to travel faster--such as Steel--and less effective against soft mediums which have them travel slower, such as many Ghost-types who are largely comprised of gas.
Offense:
x2: Steel
x2: Rock
x2: Ice
x0.5: Water
x0.5: Ghost
x0: "Soundproof" ability
Defense:
x0.5: Steel, Ice, Rock - It's like trying to hit a flame with ice, man.
x2: Electric - Scrambles the signal. (Well, at least it makes more sense than Bug-on-Dark.)
Average stats:
HP: 60
Atk: 40
Def: 80
Sp. Atk: 90
Sp. Def: 110
Spd: 90
(Based on 480 stat total)
Move examples
Most Sound moves are of the Stat category, with a few Special moves mixed in. Next to none are Physical.
Hyper Voice
Echo Voice
Ancient Song
Canon
Uproar
Chatter
Sonic Boom
Yawn
Sing
Supersonic
Roar
Perish Song
Howl
Screech
Growl
Sleep Talk
Pokemon Examples
Whismer, Loudred, Exploud (Sound)
Chatot (Sound/Flying)
Kricketot, Kricketune (Bug/Sound)
Jigglypuff, Wigglytuff (Sound)
Chingling (Sound/Psychic)
Balance
Rock and Ice definitely don't need another weakness (especially considering Sound turns many Normal moves--resistances--into weaknesses). However, this typing does give Water a much-needed buff and is otherwise quite sound. (Hohoho.)[/spoiler]
[spoiler=Egg]
Concept:
Eggs... taken literally, an egg is an unborn child. This type focuses on using them as weapons in bloodsport entertainment. How morbid.
Offense:
x0.5: Steel, Rock, Flying
x2: Psychic, Dragon
Defense:
x0.5: Fighting - Actually, most egg outer layers are very difficult with brute force compared to precision.
x0.5: Rock
x0.5: Ground
x2: Fire - Fried or scrambled?
x2: Poison
x2: Flying
Average stats:
HP: 100
Atk: 70
Def: 120
Sp. Atk: 60
Sp. Def: 110
Spd: 30
(Based on 480 stat total)
Move examples
Most Sound moves are either Stat or Physical. Next to none are Special.
Egg Bomb
Barrage
Softboiled
Shell Layer - Clone of Barrier or Iron Defense
Pokemon Examples
Happiny, Chansey, Blissey (Egg)
Exeggcute, Exeggutor (Egg/Psychic)
Togepi, Togetic, Togekiss (Egg, Egg/Flying)
Balance
A ludicrous type which would never see the light of day, surely, but every single one of its type-effective traits helps to improve balance.[/spoiler]
[spoiler=Sharp]
Concept:
Blades, claws, fangs, and spikes; cutting and piercing. It's a pretty simple concept. Of course, most of these moves will be physical attacks, and many of the pokemon
Offense:
x2: Grass, Fighting, Electric
x0.5: Rock, Steel, Water
Defense:
x0.5: Fighting
x2: Rock
Average stats:
HP: 70
Atk: 120
Def: 70
Sp. Atk: 60
Sp. Def: 70
Spd: 100
(Based on 480 stat total)
Move examples
Most Sharp moves are Physical, with a few Stats. Next to none are Special.
Slash
Vice Grip
Cut
Horn Attack
Scratch
Fury Swipes
Spike Cannon
Crush Claw
Razor Wind
False Swipe
Swords Dance
Sharpen
Guillotine
Horn Drill
Pokemon Examples
Pinsir (Bug/Sharp)
Scyther (Bug/Sharp)
Scizor (Steel/Sharp)
Gallade (Psychic/Sharp)
Goldeen, Seaking (Sharp/Water)
Farfetch'd (Sharp/Flying)
Meowth, Persian (Sharp)
Balance
I'd say it's a marginal improvement to the types' balance; nothing seems too glaring, for sure.[/spoiler]
Of course, there's also the Light type... but really, I've heard that so many times already.