Duo stages can be improved using the "both walking right" trick, which seems to be the only duo trick that works in main stages. There might be a better route.
Edit: Apparently, most of the tricks actually only work in the last stage of extra world.
#32210532858537036 - Another failed attempt at stage 6
I didn't fully understand how wrong warp works, but I tried to send the right side Satoshi directly above after reaching antigravity, possibly ending the input much faster. Unfortunately, the moving platform didn't work.
Instead, I found another trick. In addition to only one Satoshi jumping, holding L+R makes both Satoshi walk right.
Also, an unuseful glitch: you can collect a pickup without making it disappear. It isn't demonstrated in this WIP; the snapshot below was taken from another attempt.