How do you get past galactic grunt that has no Pokemon on Pokemon pearl?

First of all, do you mean the one that is blocking the Floaroama Meadow, or the one in Mt. Coronet? If it is the Floaroama town one, then go out to the route to the right, and talk to the little girl, then face grunts in battle by talking to them. If it is in Mt. Coronet, at the end of the room that is blocking a door saying that he is lost, then YOU CANT, so beat the spear pillar, then go back to there after. I think that TM02, or Dragon Claw is there. It is a great move for the Champion's Garchomp. Here are the move's info:

Name: Dragon Claw

Type: Dragon

Power: 80

Accuracy: 100

Not affected by Taunt or Magic Coat

Category: Physical Attack

Direct Attack? Yes

TM? TM02

Some Pokemon that can learn this:

Charmander evolution

All dragon-type Pokemon (for the most part, just not Kingdra, Dratini/Dragonair, and Vibrava (i think...)

Sceptile

Zangoose (i think...)

Mew (but mew can learn all tms and HMS...)