Torterra is like the worst starter in sinnoh. With it ur chances of beating the elite 4 are extremely poor. Chatot too is a Pokemon with pathetic stats. Why don't u have a staraptor?? Its much better. Gastrodon, Magnezone and Houndoom are fine choices. For more info post the movesets....
It is not possible to answer the question without knowing the move sets.
i would add in a garchomp i could not win anything but with a garchomp i was winning over and over i would also replace houndoom with strptor due to it knowing brve bird
To get a magnezone you have to level your magneton up on mount coronet
You can get Houndoom in Pokemon Platinum by evolving Houndour. Houndour can be found on Route 214 and Valor Lakefront! Houndour will evolve into Houndoom at level 24.
kirlia evolves into gardevoir at lv. 30
No. Houndoom is the final form of Houndour. It does not evolve.
Gardevoir isn't in Platinum as far as I know.
You can catch a Kirlia and evolve it into Gardevoir at Lv. 30.
you cant get gardevoir but you can catch either ralts or kirlia and evolve it int gardevoir(ralts to kirlia to gardevoir to gallade
If it is with another houndoom or ditto it shouldn't take that long.
Houndoom learns Flamethrower at lvl 48.
You can either catch a Shellos or you can find a Gastrodon in water areas I think.