What I'm wondering is double Vista or Double Nami for the orbs. Either way both will be in my party.
If you go double Nami, I'd recommend bringing Hina, if you have her, to secure the two-round burst kill. This means carefully holding PSY/INT orbs wherever you can before Garp (especially on Vista), which is a bit trickier than relying on two-unit meat orb conversion. Your Robin/Hina/Coby skill cooldowns should be medium-low (guides say 14 or less), because there's not a lot of room for stalling with such low HP. So it'd be Nami/Nami/Vista/Robin/Hina/Coby, and dropping combo would probably mean failure. All or nothing, quite risky.
Double Vista is somewhat safer, providing additional rounds to make up for bad orbs. Having an HP total over 42,000 or so is important to tank Garp long enough to kill him, so every time you sub a non-INT character in a Vista team, your other INT characters should have higher levels to make up for the HP drop. If you bring Coby, for example, keep in mind that you're giving up HP for that initial damage burst, and that dropping the combo on the first round could ruin the run. Subbing Coby for a high HP INT unit such as Krieg or Helmeppo v2 could end up providing similar damage, just spread over a few extra rounds.
In the same vein, even INT units like Towel Nami don't bring a lot of extra HP to a Vista team, though her orb manipulation skills make up for it a bit. This is why units like Broggy are ideal: Big HP + orb manipulation = breathing room for when things go wrong. That said, Vista/Vista/Robin/Nami/Buggy/Coby would probably work out okay, especially if both Vista's were at high level, like 90+.
Again, both of these INT teams only work reliably with a maxed Merry, especially the double-Nami burst. Level 70s are okay, 80s would be much better. In both teams, Vista will be both the heavy hitter and the HP tank, so he should probably receive the greatest share of any available XP.
So I don't think I'll ever get Broggy; can I still use Chopper?
If you mean for Garp, yeah, the difference between BP Chopper and Broggy's HP/Attack doesn't seem to make a difference when calculating a successful Vista run. To be honest, I didn't really understand the big push to get Broggy. It seemed pretty clear Drum was landing before Garp, and evolving Chopper to BP is far easier than farming Gaimons to bring Broggy's special to a reasonable 14 or so.
what are the suggested teams for garp with a double vista or a double g3 luffy?
The standard double Vista going around is Vista/Vista/Robin/Broggy/Buggy, with another beefy INT unit like Krieg thrown in for HP and damage, plus max Going Merry. The problem with double G3 is that, on the stage before Vista, everything but your Captains gets locked, and Coby will hit you hard. In order to have enough HP to survive, pretty much all of your team must be at or very near MAX level. Max Merry is ideal, but not required. Base is G3/G3/Robin/Coby, plus two other big INT hitters, such as Vista, Krieg, or Towel Nami.
