The best team you can possibly get in Pokemon Ruby would probably be:
Swampert
Groudon
Aggron
Flygon
Gardevoir
Linoon (For item pick up.)
good
with trading Charizard Mewtwo Groudon Raquazza Kyorge Zapdos Without trading Rayquazza Groudon Kyorge Vaporeon Gyrados Alakazam
heatran
The best team is one that has many types. Spiritomb and a dragon type Pokemon are almost certainly needed, as well as a strong water Pokemon like Milotic. The rest is up to your discretion. Without legendaries, there really are no ultimate Pokemon.
Legendary Pokemon are the best of the best you want to get: Regice, Regirock, Registeel, Kyogre, Latias, Rayquaza. This is the best possible team you can have without trading!
arceus x 6
Oddish. Zapdos. Magikarp. Jynx. Mr. Mime. Piplup.
There isn't a way you can get a full good dragon type team without trading unless you want more than one of a specific dragon Pokemon being either Kingdra or Dragonite.
whenever you want! (you need at least 2 Pokemon in your team to trade.) trade at a Pokemon center.
after pitfall valley i think.
You use action replay to get a code for 999 rare candies. It will let you have the ultimate Pokemon team
you can only get 1. beat team rocket boss he'll give you one,unless you use an a.r. to cheat that is the only way.