to catch latios with out a master ball i have no idea .
but i do no dat u can catch latios with an ultra ball.
..OK!!!

u hav to catch latias and latios with a master ball.not to fail :(
frm:
cheetah

weaken it then use an ultra ball

I caught it with a Crobat (for fly) and five Wobbufet at lv 40+. I used mean look from Crobat and when that fainted (from two psychics), I used Wobbufet's shadow tag (so it couldn't run). Then I used about 2 mirror coats (one hit psychic and one luster purge) so it would be weakened. Then I kept throwing ultra balls as my Wobbufet died. But then I caught it.

use trapinch with arena trap so latios can't excape. then freeze it or sleep it or wathever. then just barrage it with ultra balls. that's the way i caught mine. hope that helps. =)

fish you butthole

the best way is to get a wobbofet and train it to a high level..then, stack up on ultra balls..have a pokemon that knows sleeping move or paralysis move..when u find them, make sure u have wobbofet first because he has shadow tag which wont allow them to escape..make sure you get to a low health and wish for luck...hope this really works for you!

use a crobat or a golbat. use mean look to make latios unescapable. buy many ultra balls
and throw lots of ultra balls and voila, latios is at the grasp of your hands with its
ultimate power! hehe