The purpose of this thread is to document all exploits in the game and that may help in speedrunning it. Some are useful, others not so much (yet). Contributions are more than welcome.
High Jump:
There's a way to jump 2x or 3x higher than normal. Simply spam "A" while doing a mid-air kick or web shot. The more you spam "A", the higher you'll jump. Crouching also increases your jump by a little. It only works when gaining upwards momentum. Spinning kicks work best because they have the longest animation.
This allows you to skip electric suit in any%:
And here's a segment that illustrates how broken it is:
Laser 3 skip:
I haven't fully figured this one out. I know that if you jump 2 or 3 times into the laser, on a certain angle, it will then let you walk through it. Needs more testing.
EDIT: I haven't been able to reproduce this glitch on console. It may have been possible due to emulator lag.
Out of bounds in amusement park:
There are several places on amusement park where you need to crouch to get through. In those where there are enemies around, and if you get hit as you're changing from vertical to horizontal position, it's possible to go out of bounds, or at least get knocked into the wall. AFAIK only these 5 spots have enemies to knock you into the wall:
In the following example you can even finish the level while out of bounds. I haven't found a way to save time by doing this yet:
what platform are you playing on, please attach a download link or link to the website you are using, much appreciated
The only platform the game was released for was GBA. Most people run the game on emulator. Standard GBA emulator is Bizhawk, running MGBA core and TAS profile: https://tasvideos.org/BizHawk
JP version of the game is optimal for the 100% category.
I've found a potentially usable strategy in the Nightclub level. If you grab the invincibility powerup in the leftmost hostage's room you have enough time to run to Hammerhead and take him out with 4-5 impact webs similar to the strategy used against Big Wheel. Since you need to rescue all hostages to reach Hammerhead though it would require you to make that hostage the last one you rescue, meaning you'd have to backtrack from the last section to rescue them. By doing this route (hostage in starting section, hostage in upper bathroom, hostages in last section, then hostage in upper left of the dance floor area) I was able to get a time of 1:47 for the level, though the standard route got me a time of 1:43. I don't think it should become the standard but I do think it could be used as a route if an inexperienced player wanted to avoid a longer Hammerhead fight (if the RNG made him call a thug or destroy the skylight midway through if you weren't fast enough) to potentially save time.