If you feel so perplexed with my 100% original strategy, then you could switch out the magikarps with Azurills since they have splash as well. The only downside is that Azurills are slower than magicarps and you need all the speed you can get.
Too bad it isn't Black 2 since there are far more pokemon to choose from. Otherwise you'll just have to look at what you're facing
here and construct a team around it. If you don't want to grind, then it's probably best to get your team as soon as possible and just stick with them although the higher your levels, the better.
So if your starter is now an Embroar, the could choose:
Sawk/Meinshao - Probably pretty good against dark type guy
Zoroark/Krookodile - Good against ghost and psychic girls
Reuincilus - Teach it trick room (slowest pokemon can move first(5 turns)) then use psychic against fighting guy.
Chandelure - Insane base SP.ATK so you could use shadow ball against psychic and ghost girls, fire is also good against some of the champ's pokies
Ferrothorn - Defensive and support, teach it leach seed, stealth rock/spikes, thunder wave, power whip/protect etc.
This guy is actually pretty good and was used a lot in competitive play. Try and lead out with this guy and set up your stealth rocks/spikes which damage the opponent's pokemon that switch in. Leech seed coupled with leftovers will make it almost impossible to beat unless your against a fire type.
The following are just pokies with relatively high base stats:
Excadrill
Archeops
Hax
Volcrona
Legendaries
Also try and make your pokeman's movesets diverse and make sure you have a lot of restorative items and you should be good. If all goes wrong, switch back to grinding them Magikarps!