heh. but seriously. Zelda v. Zelda is NOT fun.
her moves are built to just be awkward against each other. Ftilt can beat Fsmash, but Fsmash can beat Ftilt. Dash attack is a single hit so it wins if you trade with Fsmash, but it's hard to trade. Zelda has low priority aerial approaches that will NOT go through her own Usmash, but if they connect they are madly powerful.
Farore's is easily sniped by Din's if din's is used first, but din's is easily punished by farore's reappearance if farore's is used first. if nayru's is used by both charactcters at roughly the same time, the person who uses it second will win due to invincibility frames (but only if he's only a frame or two behind, otherwise the person who uses it first will win, your invincibility frames have to be out when the other zelda's hitboxes come out).
Dtilt lock hardly works because the other zelda can Dsmash out of it. You obviously are just as floaty, so if you hover under the other zelda, uairs are hard to avoid. we all know zelda's recovery fairly well so she's easy to edgehog.
there's just so much involved in the ditto. you need to really be good at reading your foe. you have to be safe. that's what's important. you won't win if you don't take chances, but you have to take well calculated risks because zelda is better on punishment than offense in the matchup. someone HAS to take the initiative, but that's always risky.
also, keep in mind, if YOU are in range for a lightning kick, so is your oppoenent.
personally I break out sheik so it's not as boring. my sheik is used to laying zeldas so it does not have any problems with them despite what the matchup charts say. it can wrack damage up to at least 70% no prob and in zelda dittos, sheik's transform time is dramatically decreased making it really easy to switch back in.
Zelda/Sheik has at least a 55:45 advantage on zelda, but that shouldn't be surprising.