no, you cannot re-battle N agian... :'(
If you mean battle him, you do that after you beat N in N's Castle.
Nope, N won't show up again after you beat him in his Castle in Pokémon Black or White.
After you beat the Elite Four, you go into N's castle, and you catch it before you battle N.
You don't find Reshiram, it finds you right before the battle with N.
After he leaves from N's Castle you don't see him again, but Looker does briefly mention him as you round up the Sages later.
No, you dont see him again.
If you mean Reshiram, you encouter it when you battle N in his castle after the Pokemon leauge.
go to N's castle and use it to revive reshiram before your final battle w/ N.
no victini is not, thunderuos is not and the 2 that look like thunderous is not. zecrom is in the black stone in the 2nd gym leader's museum but will come out for you when you battle n in his castle
Losing to Ghetsis in Pokémon Black while in N's Castle will just have you transported to the Pokémon Center after losing to Ghetsis and then you just have to talk to the Team Plasma Grunt in the Pokémon League Pokémon Center and he will transport you back to N's Castle, you will then be able to challenge Ghetsis to another battle.
You will not be able to get the Zoroark that is on Victory Road in Pokémon Black 2 that is near the cave. That Zoroark is there to just lead you to N in N's Castle so that you can battle with him. N will battle with his Zekrom. Once you defeat him in a battle, Zekrom will revert back to its Dark Stone form and N will give it to you.
You cannot find N, the leader of Team Plasma after he leaves his Castle after you defeat him and his Dad, Ghetsis in battle in Pokémon Black and White.