Hunting
Unarmed Combat
Soldier Training
Brawling
Leadership
Guide:
1. Go along the edge of a river or lake (lake if you want to be really safe) until you find a bear.
2. Use any move that has no requirements to aggro the bear and quickly run back into the water as far as possible.
2.5. If the bear gets stuck on something, go out the water until it starts moving to you again, then run back.
3. Use call down the thunder and afk while you stockpile IP.
4. After the bear 'twitches' use OPP Knocks and get back further into the water.
5. Repeat step 4. three more times, but on the last OPP Knocks wait 1-2 seconds before using it.
6. Wait for the bear to twitch, then use 'Knock His Teeth Out!' and the bear shouldn't run away
7. Use jump twice after each twitch until at full Atk.
8. Step 4 until Bear Def meter is COMPLETELY empty, using the trick in step 5 for the last OPP Knocks.
9. Repeat Steps 6-8 until the bear dies or you run out of IP
9.5. If you run out of IP do Step 4 and then continue the fight until the bear dies

Edit: Use only lakes.