Jaffar teams

Jaffar
Ursula
Nino
Lloyd

I run my Jaffar with Eliwood, Hector, and Ninian. The plan is for him to cripple the target and everything around it with double poison strike and savage blow and then have either Ninian dance for him to finish them off or Eliwood run in and finish the target off himself (with Hardy Bearing of course). I gave Ninian Triangle Adept + Swordbreaker to take care of those pesky distant counter sword users that make up most arena teams but it could be hard to use Jaffar when the team has dragons with Distant Counter/Lightning Breath.

Either Grima using vantage and probably brazen atk/def. M.Grima is the more aggressive option but has a harder time getting Jaffar to safety. You could also go with any other lightning breath dragon with relatively high atk (A.Tiki and Nowi are the best if my memory serves), Ryoma, etc. same idea.

You could add a close counter vantage pain+ healer for more insanity.

My Jaffar is +10 and I run him with LnD3, Chill Def 3, and Atk Smoke 3 and Spd Smoke 3 as his seal. His +spd IV means with LnD3 he can double most targets or at least avoid most doubles in retaliation. Chilld Def means he'll almost never have to attack into something with +40 Def, unless there's multiple of those on a team, and having both smoke skills on top of his (eff) dagger means -7 to all stats of enemies within 2 spaces. It makes him an extremely potent debuffer (more effective then running the common Savage Blow builds imo) and with LnD and Chill Def he can also crush targets for a change, especially if they're tome users.

I run him on a team of dragons, the double debuff on def/res is double effective on them cause they can target either on ranged targets, and debuffing the atk and spd stats makes them all quite a bit tankier with their high def/res and avoiding more doubles with their attackers having -7 on spd. On top of all that dragons are mostly weak to tome users, which Jaffar is especially good at crushing.

Hope that helps.