Beating the Elite 4 (Pokemon Diamond)

Question

Okay, so in Pokemon Diamond, I'm finally trying to beat the Elite Four. And I've been doing ok...except I can't beat the Champion. I mean, i can defeat the first few pokemon that she has, but it's really a stuffgle.

I know I need to train more, but i don't know to what level. =/

Alright, here's my Pokemon im gonna defeat the Elite 4 with

Onix ~ Level 39

Staraptor ~ Level 47

Roselia ~ Level 48

Dialga ~ Level 53

Azelf ~ Level 54

Infernape ~ Level 54

I know, my Pokemon's levels are bad ( i challenged the Elite 4 with a different team), but I've been able to get up to the Champion and beat some of her pokemon. Anyone wanna help me out here?

If there's a certian level I should obtain for each Pokemon (ex. level 55 for Roselia)

If there's any items I need to buy (i have $96680; 5 full restores)

If there's any TMs i should teach my Pokemon (also include the location for where to find it)

Plus, if theres also a Pokemon I should replace (because of their type, not level) please tell me.

Or maybe the type each Elite 4 person uses, or some battle strategies.

Thanks to anyone who can answer this ^_^

Answer 1

i need help. i cant defeat the elite four and ive got a dialga lvl 56, palkia lvl 68, giratina lvl 47, torterra lvl 79, abomasnow lvl 47, and a infernape lvl 63! i need big help. i have tried a ba jillion times.

Answer 2

first evolve roselia to roserade with shiny stone.
make sure everone is 55+ and bring TONS of healing items and you will be fine

Answer 3

Alright, you're going to struggle if any of your pokemon are below level 50.  Below level 40 is NEVER going to work.  I trained all my pokemon to level 46 before I even tried Victory Road.  

My team was Gengar (Ghost/Dark), Gastrodon (Water/Ground), Torterra (Grass/Ground), Medicham (Fighting/Psychic), Staraptor (Flying) and Luxray (Electric).  I used these to make a well-rounded team.

Your pokemon are Onix (Rock/Ground), Staraptor (Flying), Roselia (Grass/Poison), Dialga (Steel/Dragon), Azelf (Psychic), and Infernape (Fire/Fighting).  This is a well rounded team as well, so you should not have any problems with type.  I reccommend evolving Roselia into Roserade if you can.

Cynthia (the champion)'s pokemon are Spiritomb lv 61 (Ghost/Dark), Roserade lv 60 (Grass/Poison), Gastrodon lv 60 (Water/Ground), Lucario lv 63 (Steel/Fighting), Milotic lv 63 (Water) and Garchomp lv 66 (Dragon/Ground).

Spiritomb has no weaknesses, so you'll have to use your strongest attacks.
Roserade's weaknesses are fire, flying, ice and psychic, so use Infernape or Staraptor.
Gastrodon's only weakness is grass, but this does 4x damage, so use your Roselia.
Lucario's weaknesses are fighting, ground and fire, which makes Infernape a perfect choice.  You could also use Onix.
Milotic's weaknesses are grass and electric.  Since you don't have electric, again use Roselia.
Garchomp's weaknesses are ice and dragon, so use Dialga.

If you want one pokemon for each of hers:
Spiritomb - Infernape
Roserade - Staraptor
Gastrodon - Roselia
Lucario - Onix
Milotic - Azelf
Garchomp - Dialga