chase it with the first team member that is faster than it and teach the mean look so the Cresselia can't run
Throw a masterball at it.
You can catch more legendary pokemons on platinum. So you can catch more on Platinum, then the other games :)
The best place is route 211 where you get ponyta (there are some).
well to opinion the best beginner in Pokemon platinum is chimchar
To answer that question, only use a Master ball when a Pokemon usually runs from a battle. The 2 perfect examples are Mesprit and Cresselia. Try your best at the rest of them. I caught Dialga with a Dusk Ball in Diamond. I've also caught a Uxie and an Azelf with a Dusk Ball in Platinum.
master ball
Arceus or Spiritomb. It depends on who your going to fight.
Throw a masterball at it.
in etrena forest
buy 5 ultra balls 5 timer balls and 5 dusk balls. cresselia is at the top the mountian. GOOD LUCK!
Master ball
You can catch more legendary pokemons on platinum. So you can catch more on Platinum, then the other games :)
There is no best pokemon, unless you're talking about legendaries. These include(Listing in two groups, extra powefull and super Powerfull) Extra Powerful Uxie Alelf Mespirit Cresselia Heatran Super Powerful Giritina Dialga Palkia
The best place is route 211 where you get ponyta (there are some).
you will encounter giratina, either catch him that's best, or defeat him
try your best to find spirtomb in Pokemon platinum
Darkrai