Help me with my team!

I didn't know where else to post this, I'm not trying to break any rules and I'm new so please take it easy on me. I did read the rules and the team is semi incomplete please don't bash on me for that just help me out please!

I'm playing pokemon platinum and I'm at the elite 4. Did fine until Cynthia then my totally unprepared full of fillers team got owned lol. So getting straight to it.

Charizard: lvl 67/razor claw/Bold
Flame thrower
Flare blitz
Slash
Wing attack
He has high special attack for me so I just mainly use flamethrower, does decent.

Gyarados: lvl 59/ wave incense/Adamant
Dragon Dance
Waterfall
Stone Edge
Ice Fang

Probably the only one done right lol. Debating if I drop ice fang for earthquake.

Roserade: lvl 55 /poison barb/naughty
Stun Spore
Giga Drain
Grass Knot
Magical Leaf

Not really sure what to do with this one.

Garchomp: lvl 58/ Adamant
Dragon claw
Crunch
Sandstorm
Dig

He's new, just been training him, no moveset yet.

Gratina filler/ comes as is from distortion world, lvl 54.

The rest is just fodder. Level wise and skill wise my team isn't doing me much in the elite 4. They're not EV trained, just basic training for the pokemon game itself.

Help me finish my team, I need to add a fighting,psychic, thunder type maybe? What should I remove/replace. What movesets should they have? I can trade to get just about any pokemon available up til gen 4 so just suggest suggest suggest! Thanks in advance for those who take the time to help me out!!

Try and keep gyarados till she has out Milotic. The mods might ask you to move your thread. Electivire does a lot to her team if you can get it Ice Punch for Garchomp. Maybe try out a hippowdon with toxic, and use that + Slack Off to stall out most of her team, then you can drop Sandstorm on Garchomp. Anyways, if you load up on recovery items you should be fine :)