Best macro controller for RNG?

Is there a controller available that is capable of getting the precise button presses needed for rng with macros?

I have been trying to get a shiny starter in fire red on the switch for a week now but it’s so hard to get it down.

If you can have macro controllers to automatic button presses, it should be possible to make one with millisecond accuracy.

Even better if you could adjust it easily too.

Any ideas on how I could make one if one doesn’t exist?