The Axem Rangers are in the Bowser in the toilet level. It's very easy to find them but it's also very hard.
1. Find the Tri-force in Zelda 64.
2. Hold reset and pull the game out.
3. Put Super Luigi 64 in the system and let go of reset while juggling pineapples.
4. You will apear in the Paper Luigi level.
5. Go to the Bowser in the Toilet level and find the key to the refridgerater.
6. Get everyone on Zebes to help you beat the mother brain.
7. Go to Twoson with everyone at level 56.
8. You will appear back at the Bowser in the toilet level and you will kill the Axem Rangers.
9. The only problem is that this turns you into Kirby. Oh well!
http://bow_papermario.tripod.com/bowsmansion/