Five Mihawks fused, two skill ups. Good start. I've only got 75 stamina, so I'm alternating the 30 and 40 stamina levels, but so far I'm getting good luck on 30 stamina drops (in fact, it took me a few tries to get my 40 stam strategy down, so most of my drops have been from 30 stam). It also lets me alternate between using G3 and Mihawk friends, so I get more attempts.
I found a variation on the double Mihawk strategy that I'm finding to be more consistent, but the units needed are a little unusual. Here's my units and levels (if you've got higher levels, all the better):
Friend Mihawk (usually above level 40)
Evolved Mihawk lv.33 (captain)
Evolved Arlong lv. 43
Evolved Morgan lv. 36
GH Usopp lv. Max (1 skill up, probably unnecessary)
Pistol Ensign lv.24, Skill level 3 (lower cool down is even better, probably needs to be at least this low)
My issues with the Gaimon lineup was that if either Mihawk or Arlong hit too many weak orbs, I simply couldn't do the damage needed to win. That has a lot to do with my lower levels, but I feel like it'd be a problem regardless. This lineup gives me four potential attackers who all have the double striker boost, if any have a weak orb, I just use them earlier.
The Pistol Ensign's attack is still low enough that he doesn't kill the Penguin, even with a matching orb (thank Enel for that penguin's defense). And his healing skill easily keeps me above 4000 to survive Mihawk's pre-emptive attack. His level probably needs to be around 20-24, though he's only doing 6 to the penguin so he could probably be stronger. The skill level's important though, I can use the skill three times during the fight.
If your Arlong, Mihawks, and Alvidas are high level enough, this strategy is probably unnecessary, but it's clearing the level easily for me.