Team Traitors
Celes (FF6)
Sialeeds (S5)
Cait Sith (FF7)
Uh... Heavy, and a rather lowish one. They spoil with status, but have major problems against teams with too many bosses, as Celes doesn't have as much time to get her stall game going.
Team Flying Traitors
Kratos (ToS)
Kain (FF4)
Jill (FE9)
Middle. Uh... Kratos is cool and all, but he can't carry a team by himself. Jill's counters are less useful in a team format, too.
Note that Sanaki is not ranked, so none of these teams have anything to fear.
Team Darkness and Light
Gares (OB)
Cecil (FF4)
Miguel (CC)
Why have a Holy Fisherman and an insane Black Knight joined forces? And where does the conflicted Cecil stand, as Dark Knight or Paladin? (I'd see form choice as definitely legal for this team!)
Feels Heavyish. TurnBlack is pretty badass here in combination with Cecil's holy damage, but Gares is such deadweight I doubt this swings Godlike.
Team Fusion
Yuri (SHs)
Kurando (SH2)
Alicia (VP2)
Godlike. Okay, Alicia won't be doing any undead-valkyrie fusing in the DL (thankfully), but Invoke Feather & Heal will do. This is kinda close to Magic Fanatic's Team Shapeshifters, so feel free to ignore it if there aren't enough slots.
Team Hard-bitten Mercenary
Gafgarion (FFT)
Watari (S3)
Selphie (FF8)
High Light. Gaffy isn't nearly as good in a team format where he can be overwhelmed. Also mostly like the conversations I'd imagine between the experienced and amoral Gaff, the quiet Shadow, and, uh, morale-improver SeeD mercenary Selphie having. It can totally be that anime with the two samurai and the random bubbly girl. EDIT: On second thought, Shadow's probably too good for light. My personal Shadow respect is quite low (don't let him throw most of the cool expensive stuff) but it seems it's better for others, and Invis Edge will spoil a lot of Light, so Watari it is instead.
Team Sage Advice
Genis Sage (ToS)
Zhuzen Liu (SH)
Saleh (FE8)
Light. Zhuzen's best damage is MT, IIRC, as is Genis's, so the team isn't as screwed as they might appear at first. (Originally had Olan here, but Galaxy Stop is actually pretty awesome in a team format, and Light needs more teams.)
Team Falenan Royalists
Prince (S5)
Lyon (S5)
Miakis (S5)
High Heavy. The Prince and his bodyguards. Rather than use cute combo attacks, I expect they'll just be smashing stuff with Unite Magic. Disable one of 'em and the fight is likely yours, but otherwise prepare for horrid overkill.
Team Just Say No
Alenia (S5)
Zahhak (S5)
Kresnik (WA4)
Light. Drugs turn out to be highly overrated, as the performance of this team will no doubt indicate.
Team Garlyle
Nana (G1)
Saki (G1)
Mio (G1)
Don't let the fact that they have a super-combo attack fool you; it isn't actually that super and they all kinda suck. Light.
Team Still in the Saddle
Marcus (FE7)
Dueseel (FE8)
FuSoYa (FF4)
Light. The arthritis isn't that bad! FuSoYa can do some mean things if he gets a turn, which he shouldn't.
Team "You cannot understand my TRUE POWER!"
Graham Cray (S4)
Evil Gaia (G1)
Augst (WA4)
Low Light. Okay, Augst isn't a final boss, but like Graham Cray his transformation leaves much to be desired. At least Gaia handed out cool tentacles to Baal.
Added a bunch of light teams, if that's where the shortage is.