Since you said "current plan", I'm going to assume that you only started the game or have not started at all. So most importantly, you'll need an hm salve. Linoone is a good choice for this and it can be caught really early. Give it the hms Rock Smash, Cut, Strength and Surf.
Now for your team, I suggest removing Gardevoir and Gallade. In game, you do not need to use psychic types, and as for fairy, the only advantage it would give would be against Drake but you have a Pokemon who can learn an ice type move for more reliable damage against him. It also gives an advantage against Sydney but Blaziken already has the fighting type. Kirlia can be a good Pokemon against Brawly, but later it is pointless to keep. It offers no advantages against other gyms unless you count Winona's Altaria. Golbat/Crobat also provides the coverage you need against Brawly as well as being 4x resistant to fighting types.
Next, for Sharpedo, I suggest you consider Gyarados as an alternative option. Intimidate is a very handy ability especially against Drake's dragons. You can use it as a water hm slave for Dive and Waterfall, the second which is a standard move for it anyway. Give it the moveset Waterfall, Ice Fang, Dragon Dance and Dive. It's role is to simply provide coverage with its damaging moves plus you won't get earthquake until later and you have Flygon for that. While Sharpedo is also a good choice, Carvanha can only be caught at route 118 and 119 while Magikarp can be caught really early. Even in dewford town you can already catch it.
If you chose to remove Gardevoir/Gallade, you will have five Pokemon at this point, counting the hm slave. You can use Kyogre as your last Pokemon but if you chose not to, I would recommend Magneton/Magnezone. It will provide you with additional help against Wallace and Winona. Its steel typing also allows you to be at an advantage against the mossdeep gym, who have rock type. Since neither of the mossdeep gym leaders' Pokemon have ground type, Magneton/Magnezone will allow you to easily defeat them as it resists all of their damaging moves.