i've just began the game, and i'm worried that since you can only battle 3 at a time, i've chose cloud/barret/red xiii as the people i want to battle, and left tifa and aeris outta the picture, should i in future installments, let them battle so they can level up to? i'm too lazy to use them and i'm comfortable with my 3 now, what should i do

It doesn't really matter who you level up. The game is incredibly easy, so just level up three for the whole game, and you won't have any trouble at all.

yeah actually you can level them up all at one time (at least in the pc version), but its a hell of a lot slower, and annoying

...plus they actually do level up with you anyways. Not as quick but when you get to level 99, they'll be around 91-2ish.

Yep, when you are level 40 your others character are lv33-34 like The bear said.

oh, and dont worry to much about aerith.

besides that, like everyone said, your characters level up with you so its no biggy at all.

Originally posted by The Bear
...plus they actually do level up with you anyways. Not as quick but when you get to level 99, they'll be around 91-2ish.
Yes, but they won't learn new limit breaks like that. So, yes, train them anyway.

I mainly leveled up just 3 characters, and i beat the game fine.