I keep waiting for this to show up here, but it hasn't.
Link's Crossbow Training to me feels like one of the ultimate games begging to be tool-assisted. It's full of tiny chunks of gameplay that even with overly trained human play simply can not be achieved, but are 'obvious' and would be interesting to anyone who's played the game to see them flawlessly accomplished.
The primary goal, after entertainment, would be highscore. This is achieved by not missing any targets to keep the multiplier going (non-issue in a TAS), by hitting targets in their center ring (3x the points, also a non-issue), by random stage objects (pots being worth roughly 10 points, multiplier is unaffected and not applied to), and then there's several 'tricks.'
In the stage with flying bird things, if they drop the target and it's shot while falling it's worth roughly 10x more points. This applies proportionally to gold targets. They will drop the target when shot, which also drops your multiplier and makes you lose points, but this is beneficial if you shoot the first several birds then shoot the targets due to the lack of score or multiplier to lose. They're also dropped when the area buzzer chimes, so keeping as many birds on the screen, and notably ones with gold targets, for when the buzzer is a keen idea.
But that stage is also one of the most problematic because it's badly effected by the PRNG. It gets bad. Some times you'll get a double drop of golds at the buzzer and 3 birds in the opening, other times nothing.
Another trick involves the scarecrow who is in most stages. He has a gut that when shot will not kill him, and will repetitively give 8 points. For the highest of scores, obviously this should be continually shot at when not shooting mission critical targets. Once his head is shot, it provides 1000 points, and should be done on the last available frame. In some stages he's out of the way (as hidden as you can get in a game with such a limited view point), and probably isn't worth bothering with. One example being the fireworks stage.
In the first stage, the first houses door can be shot and flying water melons come out that each provide 100 points, and the last providing 500. This can be repeated for the first 2 sections of this map. This is something that could help a lot more in a TAS than in a real run where zoom must constantly be used to prevent missed shots.
An obvious trick is to shoot the gold/bonus targets at their last available frame so that the multiplier can be worked up on lower value targets.
There's random doors, bells, rocks, jars, signs, etc, that can be shot through out the game, some requiring a charged shot to achieve the desired effect, some being able to be hit more than once.
Anyone got anything else? I'd love to see this happen :)