Building a Team

[The Big Al]

I'm in the process of building an actual competitive team. So far I have these two Pokemon

(Mega)Blastoise@Blastonite
Modest Nature
Torrent/Mega Launcher
252 HP/252 SpA/4SpD
Water Pulse
Ice Beam
Dark Pulse
Rapid Spin

Garchomp (needs item)
Jolly Nature
Rough Skin
4 HP/252 Atk/252 Spe
Earthquake
Dragon Claw
Stone Edge
Swords Dance

A teammate I've been thinking of is a Roserade as soon as I find a Cacturne safari so I can breed in Spikes. My planned moveset is this.
Raderade (needs item)
Modest/Timid Naure
Natural Cure
4 HP/252 SpA/252 Spe
Spikes
Giga Drain
Sludge Bomb
Shadow Ball

I haven't seen many people mention Shadow Ball on Roserade. However, it hits Aeqislash harder than HP Fire with the Natural Cure ability. It can be a nasty surprise for other ghosts and psychics attempting to which in on it too.

Another option I have been thinking on is running Toxic Spike on Roserade and have a Skarmory as my Spiker.

Any suggestions on what my last two or three Pokemon should be or on the Pokemon I have?

Thanks in advance.

 

[AnybodyAgrees]

Aura Sphere/Dragon Pulse over Ice Beam on Blastoise. Hits harder than Ice Beam with the pseudo-STAB.

 

[The Big Al]

I prefer Ice Beam over Dragon Pulse because it hits more for SE and hits opposing Garchomps harder. Aura Sphere is an option I would really like though.

 

[TerraTF]

I prefer Ice Beam over Dragon Pulse because it hits more for SE and hits opposing Garchomps harder. Aura Sphere is an option I would really like though.

252+ SpA Mega Blastoise Ice Beam vs. 4 HP / 0 SpD Garchomp: 508-600 (141.8 - 167.5%) -- guaranteed OHKO

252+ SpA Mega Launcher Mega Blastoise Dragon Pulse vs. 4 HP / 0 SpD Garchomp: 358-422 (100 - 117.8%) -- guaranteed OHKO

Both are OHKO. I'd stick with Ice Beam as its more likely for you to 2HKO Dragonite with.