Well, here we will talk about competitive ways to battle - if its OK with DP-Nish.
I'll start :
What are your thoughts about this 2x Battle combo-

Manectric - Calm (+Sp.def - Att)
LightningRod @ Leftovers
252 Sp.def 252 Sp.att 6 HP
Crunch
ThunderBolt
HP (Grass)
Protect

Gyarados - (+Sp.def - Sp.att) (Female)
Intimidate @ Leftovers
252 Att 200 Sp.def 52 HP/Spd
DragonDance
Earthquake
Return/Double-Edge/HyperBeam ( I prefer return)
Attract

I feel its a good combo cause if you manage to pull off 2~3 DDs, Earthquake
to Hell (Protect on Manectric). Return next turn.(1st turn- Attract)

Hey u didn't mention ur pokemon's levels, thats what matters most.If the pokemon is at a very high level, then it ll win no matter what moves it has.

counter a rock slide from a tyranitar first....or a breloom should spore the gyarados first and then manectric and then KILL......
PS female ttar and breloom

Swarnava......it is to be imagined that all the pokemon that are posted here are at level 100.

I say a good combo is:
Groudon (Adamant)
252 att, 252 sp ,6 hp (Scope lens)
Slash , Mud Shot , Hyper Beam , Fire Blast

with

Exeggutor (Modest)
252 Sp.Att, 252 Spd, 6 Hp
Solarbeam , Sunny Day , Sleep Powder , Synthesis

Well, let's make this thread better than Smogon itself!
This combo's also good-
Milotic - 120 Def 120 Sp.Def 134 HP 136 Sp.Att
Leftovers ; Marvel Scale
Surf
Amnesia
Recover
Psychic/ Something Good/Ice Beam

Dodrio - 252 Spd. 200 Att 58 HP
Shell Bell ; Early Bird
Tri Attack
Drill Peck
Fury Attack
-filler-

1st turn/2nd Turn - Milotic Amnesia and Dodrio Fury Att on MILOTIC (V.Imp)
If anything is a roarer/whirlwinder, kill it first
Do not use Fury Att on Milotic 2nd time if 1st time = 5 hits

Zapdos take care of Dodrio first and then Milotic

What do you mean to activate by that? If you mean to activate Marvel Scale? Well that's NOT the way to do; I'll quote:

So ya ;D

BTW, The Sunnybeam's fine, but replace Synthesis/Sunny Day with HP Fire.

Mantectric and Gyarados' movesets look fine but try playing around with Manectric's EV Spread if your going large scale competiitve as the basic 252/252/6 doesn't work in that.
Same, for you Pokémon Pranz, 252/252/6 doesn't work in large-scale competitive.

Oops Yeah, but then it's a waste coz' any status is bad including paralysis.
Well, What about single battle:

Gorebyss @ 200 Def 200 Sp.def 110 Sp.att @ Leftovers @ whatever
Iron Defense/Agility
Amnesia
Baton Pass
Surf/Psychic

Ninjask @ 200 HP 200 Sp.def 110 Spd @ Liechi Berry/Leftovers @ Speed Boost
Baton Pass
Substitute
Swords Dance
Fury Cutter

Marowak @ 252 Att 200 HP 58 Sp.def @ Thick Club @ Rock Head
Double-Edge
Bonemerang/EQ
AncientPower/RockSlide
anything

Team's good but too many BPs; (P)Hazers will gg you.
Try removing Gorebyss for Regice or some other wall.

how about something speedy with defenses to survive a belly drum?
Snorlax is no good here - one brick break from anything faster will fail the belly drum.
suggest something here!!

and please send me some info on making a good singles team! I desperately need one!!
Blissey - Pranz owes me one Chansey - Bold - He has it but refuses to give it!!!!

I'll give you some good options :-

Trust me this one kills-

Nature-Modest 252 Sp.Att,252 HP,6 Sp.Def
Houndoom@Leftovers
Crunch
Pursuit
Fire Blast
Toxic

This one is a total frustrater i.e it frustrates your foes

Nature-Adamant 252 Att,252 Def,6 HP
Weezing@Leftovers
Haze
Pain Split
Will-O-Wisp
Sludge Bomb

WTF! VAIBHAV YOU KNOW I DONT HAVE A GBA ANYMORE BUT NO! PLEASE REMOVE THAT POST AS IT IS NOT VALID.

Reply to Dark Lord:
Houndoom: Modest @ Leftovers
Sunny Day
Flamethrower/Fire Blast
SolarBeam
Crunch

Weezing: Impish @ Leftovers
Haze
Sludge Bomb
Will o' wisp
Pain Split

How about:
Metagross: Lonely @ Lefties
Meteor Mash
earth quake
Thunder Punch
Psychic