Pokémon Crystal

Legendary Dogs

Entei-lv. 40 Fire type found at random

Raikou-lv. 40 Electric type found at random

Suicune-lv. 40 Water type found at Tin Tower

TO CATCH RAIKOU AND ENTEI
1. Use a repel or super repel in an area and use a level 39 Pokémon at the head of your party.
2. Once you spot a Legendary Dog, they will want to run.  Use a Pokémon with Mean Look or Spider Web to make sure they cannot escape.
3.  Fight them till they have low hp and low stats and then throw a Pokeball at them.  The best way to capture them is to use a lv. 40 Haunter that knows Mean Look since he is not affected by normal type attacks and roar will be of no use to them nor will running.  And, you'll have enough speed to get in Mean Look before they run.  Get it asleep and lower its hp down to the red and throw Ultra Balls like crazy.

TO CATCH SUICUNE
1. Defeat Team Rocket at the Radio Tower and you should be able to get the Clear Bell from the Director.
2. Take the Clear Bell to the Building near the lake in Etruteak City and the sage guarding the ladder will let you go down.
3.  With the Clear Bell, you can now access the 3 Sage battles.  Defeat them to pass onto Suicune.
4.  When you challenge Suicune, get his HP low and lower his stats.  He will not run, so Mean Look and Spider Web will do no good.  Once you capture him, you will hear the legend of the Legendary Dogs' resurrection by Ho-oh.