Locations: Spybots, Hidden Idols, Mojo Rooms, "Combo King"
All credit for this to "Mario 1997" on gamefaqs. His guide also includes a complete game walkthrough, Mojo Room strategies, prices for upgrades and totals for skin unlocking.
SPYBOTS
-------------------
Episode 1: A New Hop---------------------------
Spybot 1: From the Spin Hover statue, get across the ledges to a stone
tilting ledge. The bot is here.
Spybot 2: Before the second set of mushrooms at the right.
Spybot 3: After Spike, move along to a barrier. Kill all the enemies
and then move forward.
----------------
Episode 2: A Succumbing To Age Story--------------
Spybot 1: After Goar, move onward, smash tree: from here, it's at the
right.
Spybot 2: After the Back Flip statue, move forward and backflip south
to the bot.
Spybot 3: After 2, drop down the ahead gap and move along the bottom
path.
------------------
Episode 3: A Zero's Journey---------------------
Spybot 1: Before the first cave.
Spybot 2: In the second arena, shoot it at the left with Snipe.
Spybot 3: At Arena 3, it's at the left.
-------------------
Episode 4: Temple of Zoom----------------------
Spybot 1: Outside, to the SW.
Spybot 2: At the east of the boss fight.
Spybot 3: At the left of the boss fight.
-------------------
Episode 5: Emerald Pity------------------------
Spybot 1: During the first slide on a ledge at the middle.
Spybot 2: At the Rhinoroller arena at the SE end.
Spybot 3: After the last slide, at the SE edge of the platform.
---------------
Episode 6: Don't Eat the Yellow Brick Load---------
Spybot 1: After the falling logs, at the left.
Spybot 2: After the set of logs you must jump across, at the right.
Spybot 3: After the Shellephant's jacked, smash the east gate to find
it on the right.
----------------
Episode 7: Blizzard of Claws----------------------
Spybot 1: After the first tunnel at the east lava. Ride a Magmadon to
it. Optionally, Hover Spin to it, quickly hit it and jump left back to
the path.
Spybot 2: After smashing the 4th node, it's at the SE.
Spybot 3: Near the Sacrifice Orb, Snipe and button on the high ledge.
-----------------
Episode 8: Life's a Beach------------------------
Spybot 1: Near the first Stench, on a ledge at the right: Shoot it.
Spybot 2: Past the stench valley behind the crates.
Spybot 3: At the water area: it's on the barrel next to the waterfall.
-----------------
Episode 9: Operation Overboard-------------------
Spybot 1: During the Mini-Boss, at the left: shoot it with Stench, or
un-jack a Titan + double jump up there.
Spybot 2: During the first slide, go left at the fork.
Spybot 3: During the Sludge fight it's in the slime: Smash it with
Sludge, or jump to it, smash it and jump back.
-----------------
Episode 10: A Sludge Too Far---------------------
Spybots 1-3: At the arena, on the outside ledges. Use Scoropilla's
Ground and Pound to destroy them, or un-jack and jump up to them.
-----------------
Episode 11: Shock and Awesome--------------------
Spybot 1: At the end of the first corridor, at the right.
Spybot 2: In the last office, at the left.
Spybot 3: In the locker room, on the east lockers.
----------------
Episode 12: Weapons of Mass Construction----------
Spybot 1: On the series of ledges, on the SW ledge.
Spybot 2: On the series of ledges, on the NE ledge behind some crates.
Spybot 3: On the conveyor belt at the left.
--------------------
Episode 13: Doomraker-------------------------
Spybot 1: At the small house, on the east balcony.
Spybot 2: At the arena in the east room, on the left.
Spybot 3: At the arena in the west room, on the left.
-------------------
Episode 14: Family Tree-----------------------
Spybot 1: At the NE of the Battler fight.
Spybot 2: Along the path after Spybot 1 on the right.
Spybot 3: At the left of the final arena.
--------------
Episode 15: Calamity Ville Horror------------------
Spybot 1: After the first arena, during the chute.
Spybot 2: After Spybot 1, along the path by some mushrooms and bunnies.
Spybot 3: During the final arena, at the left.
--------------
Episode 16: Timber Trials--------------------------
Spybot 1: After Army 1.
Spybot 2: After Army 2.
Spybot 3: After Army 3.
---------------
Episode 17: Adolt Edumacation---------------------
Spybot 1: In the hall, past the hanging cages.
Spybot 2: On the long platform after all of the mines, nodes and moving
platforms.
Spybot 3: At the area before the long stairs: shoot it at the right.
----------------
Episode 18: War of the Whirls--------------------
Spybot 1: At the left room near the level's start.
Spybot 2: During the first fight, at the left.
Spybot 3: During Fight 2 at the left.
-----------------
Episode 19: Miniority Rapport-------------------
Spybot 1: At Army 3's east.
Spybot 2: At the Brat Girl convention's southern platform, on the left.
Spybot 3: At the end of the level, on the right.
-----------------
Episode 20: Revengeance Two-The Revengicide-----
Spybots 1-3: During the second fight: one behind each machine.
HIDDEN IDOLS
-------------
Lv. 1: Bounce off one of the last mushrooms of the first set.
Lv. 2: South of Spybot 3.
Lv. 3: In battle two, smash the NE crates.
Lv. 4: On one of the staircase after the bowl room's slide.
Lv. 5: During the first slide, on one of the east hills.
Lv. 6: When jumping across the second set of logs, it's to the left.
Lv. 7: During the boss, unjack+ double jump off a magmadon in the left
lava.
Lv. 8: At the start, to the right, behind a pillar.
Lv. 9: At the slide's fork, go right.
Lv. 10: After the vines, above the plant.
Lv, 11: In the third to last office go south and smash the icicles.
Smash the shelf here for the idol.
Lv. 12: ...Above your head at the start.
Lv. 13: In the first fight, behind the east machine.
Lv. 14: During the first slide.
Lv. 15: Along the set of mushrooms.
Lv. 16: During the first chute.
Lv. 17: In the area before the boss, at the left.
Lv. 18: In the final room, behind the chair.
Lv. 19: The chute after army 4.
Lv. 20: During fight 1, unjack Scoropilla to grab it.
MOJO ROOMS
-------------
Lv. 1: Near the second waterfall, on the right, before the water.
Lv. 2: By Spybot 3.
Lv. 3: After the first tunnel, run along and jump across east ledges.
Lv. 4: At the SE corner of the bowl room.
Lv. 5: At the SE of the Rhinoroller area.
Lv. 6: After falling logs, to the right on path.
Lv. 7: East of Spybot 3, fall down.
Lv. 8: Before final chute, at the left.
Lv. 9: After the chute filled with slime, to the left.
Lv. 10: SE of the platforms leading to mini-boss.
Lv. 11: On top of east lockers in locker room.
Lv. 12: Left of conveyor belt behind the machine.
Lv. 13: Past the east room's coveyor belt on the right.
Lv. 14: Before Voodoo Bunny camp.
Lv. 15: After the first chute, to the right.
Lv. 16: After Army 3, in the tunnel.
Lv. 17: Ahead of Spybot 2, near Ee-lectric.
Lv. 18: Take left path at beginning.
Lv. 19: Go east after first set of Brat Girls.
Lv. 20: On one of the first platforms you run across.
PLACES TO GET "COMBO KING"
-------------
Lv. 1: In the valley after you meet Ratnicians.
Lv. 1: When saving Aku Aku.
-------------
Lv. 2: At the level's end on the small ledge.
Lv. 3: During Arena 2, when the Ratnicians attack.
Lv. 4: At the small arena with two switches, where you must extend the
tongue: do it with Ratnicians.
Lv. 5: Before fighting the Rhinoroller, on the Koo-Alas.
-------------
Lv. 6: On the first gear: do it on the spikes.
Lv. 6: After the falling logs: do it on the Koo-Alas.
Lv. 6: In the Rhinorollers fight: jump off Rhinoroller and do it on
Koo-Alas and the stunned Rhinoroller.
Lv. 6: Before fighting Shellephant, do it on the Koo-Alas.
-------------
Lv. 7: On the Magmadons at the start.
Lv. 7: On the Koo-Alas before the boss.
-------------
Lv. 8: On the first set of Doom Monkeys.
Lv. 9: On the Doom Monkey waves in the mini-boss.
Lv. 10: On the Doom Monkeys after the vines.
-------------
Lv. 11: The monkeys in Corridor 1.
Lv. 11: During the offices.
Lv. 11: In the locker room.
-------------
Lv. 12: At any arena, line up 3+ Raticles. Freeze them closely and then
slap them.
Lv. 12: On the spinning platforms, do it on the monkeys.
-------------
Lv. 13: During the first fight, unjack a Raticle and Combo King on the
monkeys and it.
Lv. 13: During fight two, unjack Stench at the end and Combo King it.
Lv. 13: During fight 3, line up 3+ Raticles to freeze closely and then
slap.
-------------
Lv. 14: At the Voodoo Bunny camp.
Lv. 14: At the ending bunnies.
-------------
Lv. 15: On any platforms with 2+ bunnies.
Lv. 16: In Army 1, Combo King the bunnies.
-------------
Lv. 17: Near Spybot 2: un-jack Ee-lectric to Combo King.
Lv. 17: Use Ee-lectric to shoot the trapped Shellephant ahead of Spybot
2 30+ times.
Lv. 17: During the Uka fight, line up 3+ battlers and Uka to use
Cyclone Storm on closely. Afterwards, slap them a few times.
-------------
Lv. 18: On the first Brat Girls.
-------------
Lv. 19: In the third army, on the outside of the cauldron.
Lv. 19: In the third army, on the central platform.
Lv. 19: In the fourth army, on Ee-lectrics.
Lv. 19: In the Brat Girl "convention" on any platform.
Lv. 19: In the sixth army on Magmadons.
-------------
Lv. 20: On the first brat girls.