Pokemon-go – Will Feebas’ distance travelled still count towards the evolution requirement if I unbuddy it now

When you evolve a Pokemon, its CP circle stays as full as it did before.

As a result, it really doesn't matter in which order you boost a Pokemon. However, you should keep a few points in mind:

• Powerups cost more Candies the more CP a Pokemon has (based on a Pokemon's level).
• Powerups cost more Stardust the more CP a Pokemon has (again, based on level).

Cost will increase every second powerup.

Therefore, it makes sense to power up a Pokemon until it is near the upper end of your CP ring. As the ring stays in the same place, it will give you a rather decent CP per Candy ratio.

For example, if a Pokemon's max CP was 515 and it is currently at 425, it would make sense to power it up to 500 or more. At that point, you should evolve it, provided you have the candies.

Overall, you'll still be using fewer candies because you're doing most of your evolution on the lower side of the scale, and using the Evolution mechanic to sharply spike the Pokemon's CP.

Based upon my time playing Ingress (created by the same company and also using a lot of the same infrastructure it seems), you can go at least 15 mph (~24km/h) and it SHOULD still track you. (This is a little less than the 30 kph someone in the comments mentioned).

Note that 15 mph is a 4 minute mile (or 2.5 minutes per kilometer). This is a little slower than the record running speed, and still over the average biking speed.

It also doesn't tend to lock you until you've made multiple jumps at faster speeds, and it only does so to stop spoofers.

Therefore I doubt it is your walking speed.

If your game isn't registering your distance, I would assume it is either GPS troubles, the game in general, or server issues. The majority of this is handled by Niantic and will likely improve as the game progresses. Unfortunately, that means there is probably little you can do other than contact Niantic to let them know.