Ape Escape 2: RC Car Training & Stage 8: Ninja Hideout (12/15 Monkeys)
Before Jimmy tackles on the Ninja Hideout, Natalie sends him the RC Car. Since the Professor had to return from his vacation early, he will be alongside his granddaughter to help Jimmy out, just like they did with Spike in the first game.
The RC Car is the last of the first game's regular gadgets (though if you beat Specter in that game but kept playing from there, there's actually one more to get). Using it in this game is exactly the same as before, including being able to destroy it yourself.
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The Ninja Hideout level is kinda cool, because this is when the apes will start wearing different outfits to based on the stage they're in. This is different from the special monkeys that the Monkey Radar identifies as a multicolored "??? Pants". Some of these monkeys will dress up as actual ninjas that still based their colors on the pants they would've otherwise been wearing.
These ninja monkeys will throw shuriken stars at you from a distance, and if you manage to knock them out with the Stun Club, they will go through an overdramatic fainting sequence, which you can stand and watch right before you decide to catch them.
Catch at least 12 apes to move on. There's gonna be another boss battle coming right after this!