Help for pokemon platinum team!!!

Okay, I'm in a bit of a dilemma.

My two favourite Sinnoh pokemon are Garchomp and Gliscor. I'm gonna start playing platinum for the first time soon, so I don't know how they perform ingame.

Here's my current planned out team:

Infernape, Luxray, Roserade, Garchomp, water type (haven’t decided yet)

I was wondering if Gliscor is underwhelming if I use Garchomp? Obviously both can't have earthquake, but is that a massive problem? Should I just use Staraptor instead, even if I like Gliscor more? There's also that shared 4X ice weakness... does it matter?

I'll appreciate any input. Thanks :)