Yeah, neither of these are too tough.

There are some general strats that have been listed but the reader should understand that not all of this or any of it is necassary.

-KoTR is a very strong attack, this can be effectively combined with W-Summon for two casts or HP Drain, which will heal you ginormous amounts every turn.
-Another summon, Hades is very useful against Ruby, which will be paralyzed for 15 (or a lot) of turns.
-Most players that can't beat the WEAPONs won't have master materia, so those suggestions won't help, if for some reason you do have it then it'll allow you to combine multiple materia with KoTR.
-I thought I should mention the cheepest way, if you use Cait Sith's limit break slots and get all Cait then you'll kill either. There is a way to slow the slots down but I don't remember.
-Lucky 7s can help. If you have 9999 HP against Emerald and have two materia equipped it will deal 2222 (1111x#of materia equipped) and bring you to 7777 which will cause all attacks to deal 7777.
-Underwater materia is gotten by going to the place you got the submarine and killing a ship enemy with the morph command. You'll get a guidebook which can be traded to a man in Kalm for the underwater materia.
-Final Attack (achieved through the battle arena in the golden saucer) is great, it allows you to cast a spell at death, I recommend Phoenix against Emerald and Revive against Ruby.
-Which brings me to the point of using one character against Ruby, it's whirlwind attack can knock a character out of the fight, to avoid this have one character with all your best stuff and fight it solo, otherwise your best guy could be knocked out of the fight. This is why to connect revive to final attack, so only the one character is healed.
-You don't need to master any of the above, though it helps.
-HP pluses are useful (they're bought at Cosmo Canyon).
-Gravity materia does heavy damage to Emerald.
-4xSlash and hero's drink are very helpful if you're not using KoTR.
-Mimic is the uberness. It as the name implies allows an attack to be mimicked such as w-KoTR.
-Counter combined with mimic means as a response to any attack you counter with your last move, which might just happen to be w-KoTR.