(I understand EV's, but I don't properly understand how to train for them, and such... Also don't know how to see the EVs they already have, so I can't help too much in that)
Emolga:
Nature: Calm
Ability: Static
Volt Switch
Acrobatics
Pursuit
Thunderbolt
Camerupt
Nature: Gentle
Ability: Solid Rock (Which helps with 4x weakness A LOT!!!)
Item: Hard Stone
Flash Cannon
Overheat
Earth Power
Rock Slide
Greninja
Nature: Sassy
Ability: Protean (Because seriously... He's so crippled without it)
Item: Amulet Coin (That's what's on him, but I forget what I put on him when I battle... I've been hatching a lot of eggs lately, so I'd have to search for that)
Ice Beam
Nigh Slash
Surf
Extrasensory
Ludicolo
Nature: Hasty
Ability: Rain Dash
Item: King's Rock
Energy Ball
Ice Beam
Brick Break
Hydro Pump
Flygon
Nature: Sassy
Ability: Levitate (Adds an extra immunity)
Item: Rocky Helmet
Dragon Tail
Crunch
Earth Power
Rock Slide
And then as I said I often change out the last pokemon. I like to use Emolga/Flygon Strategically, for not only their resistances/imunities (as I can switch to them to take zero damage at times, and then use one of their moves that changes them while switching out pokemon, leaving the opponent to (Most likely) use a move fitted to hurt Emolga/Flygon or switch, offering me in some free damage on them. Having Greninja have a vast type of moves, it also helps to further this strategy, if I plan ahead. I could also leave emolga/flygon there if I feel they expect me to switch them out (usually not first time I have opportunity for it though.) I also like to keep them around, because a good bit of opponents won't exactly expect a camerupt/emolga, which might help. I've been overwhelmed, by a pokemon I've only seen once or twice, because I didn't know who he was, and what the moveset was. I really feel like I should keep flygon in party instead of switching it for garchomp, but I do not claim to be a pro at it though, because for 90% of my life I have just been playing casual, which I know is a million times easier. As I said earlier though... I legitamately don't know how to get Rotom... I've only seen it when fighting against other players.