Pokemon Platinum Team help

[Howlcall]

So I have beaten the elite four. Become the champion! I have watched the credits roll and felt quite pleased with myself as I think we all must when we accomplish defeating Cynthia and her Garchomp. However, now I am into the end game content. My favorite place. And I have found myself faced with my age old enemy.... Only one tm for roost. So I am looking to this wonderful community for some helpful advice and tips. I am always learning lots of new things here after all. <3

Here's the issue:
Togekiss: calm (My Para-flinch master)
ROOST<---
thunder wave
aura sphere
air slash

Scizor
ROOST <---
Bullet punch
swords dance
-------

Garchomp
(need suggestions)

This team is ultimately going to be the beginnings of my ultimate team and hopefully take down that tower tycoon Palmer... oh how I dislike Palmer...

Anyways I need a lot of help. I absolutely must have a roost on a pokemon but I can't seem to get another one from anywhere or breed it to these pokemon. please help my team!

Also, my favorite pokemon is arcanine. I've recently been playing on pokemon Showdown and getting better at competitive battling... only to find arcanine quite lacking. Please help with a moveset for him as well if possible.

Arcanine
Ability: flashfire


Thanks in advance,
Howlcall

 

[Hiatus]

For Garchomp, I'd suggest having Earthquake, Dragon Rush, Stone Edge, and Crunch. Earthquake allows you take down a variety of fire- and rock-types, and with Dragon Rush, you're able to defeat any opposing dragon Pokémon. With Stone Edge and Crunch, you have chance to cover flying, ghost, and psychic (as well as a couple of others that I can't exactly put my fingers on right now). If your Garchomp has Sand Veil ability, then it's recommended to have some Sandstorm user on your team, so that it could take full advantage of its effect.

 

[Howlcall]

Sounds good. I'd think the wide lens would be the best hold item for the garchomp, yes? to up the accuracy of his moves. as for a weather summoner, do you have any suggestions? As you can see I have two maybe three empty slots on my team. I feel giving garchomp sandstorm might immediately boost his ability but it'd waste his immense power and speed on a turn, which could cost him some serious hp.

 

[Hiatus]

Sounds good. I'd think the wide lens would be the best hold item for the garchomp, yes? to up the accuracy of his moves. as for a weather summoner, do you have any suggestions? As you can see I have two maybe three empty slots on my team. I feel giving garchomp sandstorm might immediately boost his ability but it'd waste his immense power and speed on a turn, which could cost him some serious hp.

Oh, of course; my suggestion would be Hippowdon. Now, since both Garchomp and Hippowdon are weak against ice, this combination would make you particularly vulnerable to them, but thankfully, latter's got enough health and bulk to withstand their attacks, so it shouldn't be any trouble for you! Plus, it's got access to Slack Off, if I'm not mistaken, and with that, you'd be able to recover itself at any time.