The co-op jump is used extensively in the current any% WR by NEG_taro. Check it out in
this Nico playlist.
It's been a while since I tried it myself, but I believe you're supposed to point the P2 Wiimote at Mario, and then press A on both Wiimotes at the same time (within a few frames of each other). As you'll see in his camera, when he needs to do co-op jumps, NEG_taro actually uses his foot for one Wiimote (the one he uses just for pressing A, not for aiming).
The co-op pointer is also able to stun enemies. See Good Egg 1's boulder planet, or Drip Drop's eels for good examples. It can also manipulate the bouncy plants like on final Bowser phase 2.
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Also, since the any% route and starbit collection were asked about earlier (something along those lines at least):
My any% route's Hungry Luma stars are Sweet Sweet (Terrace), Sling Pod (Fountain), and Drip Drop (Kitchen). In my
segmented Luigi any% run, these were around
33,
21, and
22 seconds respectively, from beginning of control to the star cutscene. These star times are easily some of the fastest in the game.
The other Hungry Lumas are Bigmouth, Sand Spiral, Boo's Boneyard, and Snow Cap. Sand Spiral and Bigmouth are each 45-60 seconds from what I recall, and can't be sped up much to my knowledge. Boo's Boneyard and Snow Cap are at least as long, and they also require getting the Grand Star from the Engine Room, which takes a while due to the really long cutscene of the Garden opening (and I didn't think the Garden stars were short enough to make up that time).
Some RTA players actually leave out Sling Pod and Drip Drop because they are hard to consistently get good times on, but they are excellent for segmented or TAS runs. (I'd love to see a Sling Pod TAS, by the way!) But even for an any% TAS, 3 Hungry Luma stars is still the maximum we'd probably see, for a couple of reasons. First, it takes a bit of time to get to the Hungry Lumas and feed them, offsetting the benefit you get from the short stars themselves. Second, every time you finish a level with star bits, you have the "You got some star bits!" dialog at the end of the level, which usually* wastes some time.
(*After you finish a star, even if "You got a star!" is the only dialog present, the game actually makes you wait a couple of seconds before you can proceed to the Save prompt. So a couple of seconds of dialogs won't hurt you at all. But if your dialogs last longer than that, you will be wasting time. So if you get other dialogs like unlocking a new galaxy, a new storybook chapter, etc., a starbit dialog will hurt you more. For the same reason, you should usually try to finish with 0 coins if you can.)
I might try to help fill out an (RTA) IL table for this game. Even if many of them would just be me cutting parts out of my segmented run, I guess that would help for convenient reference.
