The Road Less Traveled By

Gigalith@normal gem
sturdy
nature:naughty
-Stone Edge
-EQ
-explosion
-stealth rock

Emboar@quick claw
blaze
nature:naughty
-fire blast
-scald
-grass knot
-hammer arm

Galventula@electric gem
compound eyes
nature:mild
-thunder
-energy ball
-disable
-bug buzz

Sawsbuck@life orb
sap sipper
nature:naughty
-horn leech
-megahorn
-nature power
-return

krookdile@muscle band
moxie
Nature:jolly
-Eq
-crunch
-rock slide
-low sweep

jellicent@wise glasses
water absorb
nature:modest
-scald
-grass knot
-shadow ball
-ice beam

It's better to put in EVs for your Pokemon.

Anyway, Gigalith is better off with Adamant so that its Special Defense boost in Sandstorm (if it happens) isn't wasted when it's Naughty. (use 12 HP/252 Atk/244 Spe)

Using Special Attacks on Emboar isn't usually a good idea. Flare Blitz hits harder due to its better Attack stat:
-Flare Blitz
-Wild Charge
-Superpower/Hammer Arm
-Earthquake/Head Smash
Nature: Adamant/Jolly
EVs: 252 Atk/4 Def/252 Spe or 212 HP/252 Atk/44 Spe
Item: Choice Scarf/Choice Band

Use Volt Switch instead of Disable on Galvantula, since it's too frail to make use of Disable. (use Choice Specs as the item; EV spread should be 252 SAtk/4 SDef/252 Spe)

Give Krookodile Choice Band as the item and Stone Edge over Rock Slide. Replace Low Sweep with Pursuit (but you have to breed for the latter). Use 4 HP/252 Atk/252 Spe as your EV spread.

Replace Megahorn with Swords Dance on Sawsbuck; sometimes 100 Attack isn't enough to hit things hard. (use 252 Atk/4 Def/252 Spe as the EV spread)

Jellicent is best played defensively, due to its good defensive typing:
-Scald/Surf
-Will-o-Wisp
-Recover
-Taunt/Shadow Ball/Ice Beam
Nature: Bold
EVs: 248 HP/216 Def/44 Spe
Item: Leftovers