If Nanoha will be presented, I'm sure that she'll be one imba servant probably because of the shitloads of offensive magic that are rated A and some EX, damage dealt will reap of untold numbers and she can literally take on probably two or three servants in one go...
If i should categorize MGLN characters to Servant Classes...
Nanoha: Archer or Caster. Fate: Saber or Berserker. Archer, Lancer, or Caster can theoretically work too. Hayate: pure Caster. Signum: pure Saber. Archer can theoretically work (she has only Sturmfalke for long-range IINM). Shamal: pure Caster. Vita: Berserker or Lancer. Archer can theoretically work too (steel balls flying). Chrono: Caster or Rider (hey, he's an battleship captain). Yuuno: pure Caster. Assassin is theoretically possible (a puny ferret? Wait until said ferret slits your throat in your sleep!). Subaru: Berserker or Rider. Lancer and Saber theoretically possible (she's a close-range fighter anyway) Teana: Archer. Limited options as Caster. Caro: Rider or Caster. Elio: Lancer, Saber, or Berserker.
Dunno much about Jail's numbers and everything after them though.
Astana said: Yuuno: pure Caster. Assassin is theoretically possible (a puny ferret? Wait until said ferret slits your throat in your sleep!).
Not to mention he's shown the ability to, unlike any other characters to date, teleport unwilling targets. So what's to stop him from teleporting you into the sun? Or teleporting pieces of you? If he were a combat-oriented guy, Yuuno could do some really nasty crap.