I would have to go with Team A since Lelouch, Issei, Madara, Rin and Riser each have great abilities that could defeat most of them, except Light, Eucliwood and Zeref would make it challenging.
Challenge accepted
Also Zeref and Eucliwood's death magic won't work on either Madara or Riser since Madara is already dead and Riser is immortal unless he was doused with holy water.
Considering Lelouch has Geass, he could control anyone he wanted on Team B.
Haruhi is pretty much god of the universe, so...it kinda explains itself.
Madara could kill pretty much everyone on Team B.
Rin is half demon, half human, so he's useful somehow.
Team B:
Ichigo could kill a lot of people on Team A, probably.
Light has a Death Note, but it would be pretty bad if he didn't know the other people's names...