Tsuru: HP: 1151. ATK: 1210. RCV: 366. Rank: 6.5/10 Special: Heal 2000 and Shuffle Orbs. Tsuru has a decent heal for a special which might be able to help you out. She also has pretty nice stats (besides her health). She can be useful.
Choo: HP: 768. ATK: 492. RCV: 256 Rank: 1/10 Special: 5X damage to all enemies. None of Choo's stats are good. The only thing average is his RCV, but it's just average. That alongside a crummy special make Choo a terrible unit.
Zephyr: HP: 3702. ATK: 1252. RCV: 88 Rank: 9/10 Special: 1.75 boost to Shooters for 2 turns. Zephyr's boost to Shooters is incredible and so are his stats. Even if he's not your captain (which he should be), Zephyr should still be included on all Shooter teams.
Curiel: HP: 2470. ATK: 1359. RCV: 252 Rank: 7.5/10 Special: Middle row orbs into either STR or DEX, Bottom row orbs into either PSY or INT. Switch Orbs once. Curiel isn't the most reliable Orb converter, but with multiple colors, it's hard to find reliability. Curiel has amazing stats and his special allows you to switch orbs. Curiel does a lot.
Don Krieg: HP: 2734. ATK: 1057. RCV: 172. Rank: 6/10 Special: Poison all enemies. Yes, Don Krieg has powerful stats, but his special sucks. His stats are the only thing good about him, but they're not good enough to make him one of the best.
The Unluckies. HP: 596. ATK: 893. RCV: 130 Rank: 4/10 Special: 25X damage to 1 enemy. The Unluckies will not provide you any luck for your team. Only thing decent about them is their ATK. Everything else is pretty crummy.