Raikou is a roaming legendary Pokemon. Whenever you find him, he runs away. He runs all across the region because he feels like it. He has been spotted in many places, including a strip club, a raft in the middle of the ocean, the Titanic, entering a Time Machine, generic patch of grass 547, a -5000 star hotel, Hell, Antartica, Smash Bros Signups, the UFO, on this wiki, in Poyo Ride's House, on an elevator, and the list goes on and on and on and on and on and on and HEY IS THAT RAIKOU IN THE PACIFIC OCEAN XDXDXDXDXDXDXDXDXDXDXDXDDXDXDXDDXDXDXDXDDXDXDXDXDDXDXD.
After the Kyurem Battle, Raikou can spawn in the overworld. He has ridiculous stats, but gives 4 DX beans, DX gear and a ton of EXP. However, there is a 20% chance each turn he will run away. This can be 0% a turn if you dodge all his attacks. Raikou's first spawn is scripted straight after Kyurem gives you a cure piece. Kyurem then explains what Raikou does. If you beat Raikou, Kyurem's dialouge differes and he accuses you of hacking.
It is impossible to die during the first fight as Raikou takes place right after Kyurem's fight without a chance to save. You are left with 1 HP and if both Kirbies have 1 HP Raikou flees.
Raikou hits the kirbies with lightning bolts. Can be jumped over.
Raikou runs into the Kirbys. However, if jumped over instead of jumped on, he starts to run away. The kirbies chase after him, and jump on him. (Similar to how Mammoshka is defeated in Dream Team, but sideways.) If a jump fails, Raikou runs away.
"That was the legendary Raikou. He is a very strong Pokémon, but beating him gives you sexy rewards. However,he flees often, so if you see him, be prepared."
—If Raikou flees
"What the truck, you beat Raikou. Are you hacking the game. Why didn't you hack in the cure pieces. Anyways, Raikou is a strong enemy who often flees and gives sexy rewards you can easily hack into the game."
—If you somehow beat Raikou.