Emulator

Game Name?
Tested: Super Monkey Ball 2

Game ID?
GM2E8P

What's the problem? Describe what went wrong in few words.
The default control pad radius of 69 is too low, resulting in Stage 1 taking 8.24 seconds to complete due to less joystick push. (51.76)

What did you expect to happen instead?
The default control pad radius produces the same results as console (6.82 seconds) (53.18)

What steps will reproduce the problem?

1. Load Super Monkey Ball 2.
2. Main Game -> Story Mode -> Create a file
3. Press Start to skip cutscene.
4. Select Simple. (Press A)
5. Hold exactly forward on the control stick. (Easier if mapped to keyboard)

Dolphin 3.5 and 3.5-367 are old versions of Dolphin that have
known issues and bugs, so don't report issues about them and test the
latest Dolphin version first.
Which versions of Dolphin did you test on?
4.0-3644 (not redownloading Dolphin every day)

Does using an older version of Dolphin solve your issue? If yes, which
versions of Dolphin used to work?
At some point, the radius option used to be 100.

What are your PC specifications? (including, but not limited to: Operating
System, CPU and GPU)
Windows 3.11, Intel i486DX, S3 86C911

Is there any other relevant information? (e.g. logs, screenshots,
configuration files)
Super Monkey Ball 2, Simple stage.
Dolphin, Radius = 69: 8.24 seconds (51.76)
Dolphin, Radius = 100: 6.82 seconds (53.18)
Real console: 6.82 seconds (53.18)

The correct radius is at the very least 77, which is the first number that produces 53.18 seconds remaining, the correct result. That causes it to saturate at almost exactly 100% push. I hypothesize that Super Monkey Ball saturates at less than completely pushed joystick, meaning the true radius is more than 77.

A better way to test would be homebrew which simply reads the controller data. If the devs have already tried that, then obviously there was a mistake somewhere.

I'm not sure how this bug relates to Wii games.