pokemon platinum good team?

I suggest taking out the legendaries. People wont appreciate battling you because of them. Try a better fire type like Typhlosion, Arcanine or even Camerupt. Then I suggest a Metagross to substitute Dialga.

Rock Smash Dialga is pretty sucky. Delete rock smash with the move deleter. Put something else there.

Lucario could use a steel type move, which would get a boost from its STAB.

Raichu is okay, but could be replaced with a pokemon in a higher tier.

Milotic is a bulky water choice, aqua ring could replace whirlpool. Waterfall is not a very smart choice for milotic though being a special attacker.

Some of the only GOOD HM moves are surf and waterfall, surf for special attackers and waterfall for physical attackers, so get rid of some of your HM moves. Try using an HM Slave instead. Have all your HM's on an under-leveled pokemon used solely for the purpose of being a slave. It keeps your other pokemon to focus on battling.

Also, replace bite with crunch on your crobat, the flinch factor doesn't make up for its low power. Try a poison attack that will add to it's STAB. Or maybe toxic. Toxic will poison your enemy badly which is always an advantage over regular poison stat.

For more info look up a little website called smogon.

In game (Which i'm assuming this is, as many of your pokemon have HM's) this team would work easily. However, if you want to battle competitively, you may have to make some adjustments. Some of your Pokemon are using both special attacks, and physical attacks. It would be better to concentrate on one of these per Pokemon, as you can dedicate the EV's towards these attacks. As well as this.

Take a look at the base stats of your pokemon, and decide what type of moves you should be using for them. www.gamefaqs.com has a lot of comprehensive FAQ's on batting, team building, and move sets - take a look there if you want a bit of help.

Take out the legendaries and get rid of surf on milintic and teach it toxic