Stream:
To have a stream hitting a certain spot with every shot aim at a 45 degree angle on either side. Shooting at 37 power also will result in the stream landing just outside of your aiming circle, making it easier to hit shots.

Creek
Creek is relatively similar to stream. Aim it with a 45 degree angle to allow it to hit a tank with every shot. However, the spread is slightly wider making it less effective at longer ranges.

River
River is again similar to its downgrades but has a much larger spread, making it very hard to hit every part of the shot on one tank. However, aiming at 45 degrees will work so long as you aim 1-2 power past your intended target. River however won't hit in 1 single spot at longer ranges.
For reference, 87 power with any of these will hit across map.

Flame + Blaze + Inferno
Flame, whilst being a weaker weapon becomes very effective when upgraded, dealing good damage. Because of that, it's good to know how to hit it perfectly. Generally Flame and Blaze have a fairly stable spread and aiming at 45 degrees should keep it all in one spot with a few stragglers landing just on the edge. However Inferno may miss a few flames when aiming at 44 but will still hit the majority of its flames.

Fleet
Having a fleet hit all in one spot is both deadly and effective at dealing large sums of damage. This can be done by aiming at a 45 degree angle. Fleet works at shorter distances but may becoming slightly off when firing longer distances as it begins to spread more.

Fun fact: Super Fleet (which is an upgrade of Heavy Fleet) deals less damage than Heavy Fleet at close range.

3-5 Ball
When firing a 3 or 5 Ball aiming at a 45 degree angle will cause every ball but 1 to land in the same spot (tested for short distance, with long distance shots 2 will sometimes miss). Again, the 37 power and 45 dergree angle can be use to hit right outside the aim circle.

Have not been able to test 11 ball or further but will update this when I next test them.

Maximum roller distance
Any roller variant will never travel further than a full aim circles length, with it going just over half the diameter of your circle from where it lands. This is the same for heavy, grollers and back variants.

50 Power
3D Bombs fired at 50 power no matter what angle will all go 1/4 of the distance of the map.

100 Power
Regardless of any angle, the furthest distance a 3D bomb can go is half the distance of the map at 100 power.

Along with this, any 3D bomb fired at 33 power will hit just outside the aiming circle.

Cross map shots
Any regular shot fired at 66 angle (either side) and 100 power will sail completely from one end of the map to the other.

Half distance shots
Likwise, any shot fired at an angle of 79 and power of 100 will hit a target exactly halfway across the map.

Counter 3-4k
Counters, often being regarded as being one of the worst weapons in the game, can actually do a decent amount of damage if hit right. Counter 3-6k will all hit a target if aimed at a 45 degree angle, dealing around 30-50 dmg depending on crits and terrain shape.

Ringer
Ringers generally being good shot gauging weapons are very useful for close range shots that can still be taken from behind cover or through terrain, a normal ringer will hit a target (when aimed straight down) that is around a third away from the centre of your aiming circle.

Heavy Ringers
Heavy ringers will hit any targets that are roughly 2 thirds distance from the centre of your tanks aiming cricle.