If it's on 1hp and asleep, there's nothing more you can do to make it easier, however using a different type of ball should help, Ultra's are good all-rounders, but you can boost your chances with the specialist balls. Fast balls are your friend in this case, being twice as good as Ultras when used on anything that flees from battle. (They also use up those not-so-great white apricorns).
Also, if you want to see your chances, you can them see here [http://veekun.com/dex/gadgets/pokeballs?pokemon=Raikou¤t_hp=1&status_ailment=SLP&level=40&your_level=0&terrain=land]. It can calculate the chances of catching anything with any type of ball in fact.
xAFROMANx said:
Famous Anus said:
Dusk balls at night/in caves seem to be the best thing for me.
is it even possible 2 meet raikou in a cave?
You can meet them on water! Makes sense in one of their cases, but that one waits patiently now, doesn't make that much sense for the other two however.