You can't catch Zekrom in Ruby version.
Yes. Zekrom is White's legendary. Reshiram is however unavailable.
You can't catch a sentret in Ruby version, but you can catch one in Emerald version.
You can't. If you want a Zekrom, you have to trade with someone who has Pokemon White
No. Reshiram is exclusive to Pokèmon Black Version, whilst Zekrom for White. It's just like you can't catch Dialga AND Palkia on Diamond or Pearl.
you catch zekrom while you are versing the elite four for the first time. you will be able to catch it just before you verse N
You cannot catch Ponyta in Ruby version, nor Sapphire version. You much catch it in Fire Red or Leaf Green and then trade it to Ruby or Sapphire.
Zekrom is in both games, however, you may catch it in white version.
Yes, if playing White Version.
You can catch Zekrom in Pokemon White and Reshiram in Pokemon Black. They are version exclusive legendaries so the only ways you could get both is through hacks or trading with someone.
It will appear after the elite four, but before fighting N.
No you can't catch darkrai in ruby unless you hack (witch i do not recommend)
Zekrom, and the best way to catch it is to keep your master ball and catch it that way, cause that's how I did it.