Optimization: Revision of NPC Pokémon matchup algorithm to ensure balanced battled

[z-q-ying]

As a Trainer, I want NPC Pokemon to have similar strength to my chosen Pokemon during battles. This will make fights fair and fun.

Depends On:

• 36

Acceptance Criteria:

• [x] When I battle an NPC, their Pokemon's level and stats should be close to my Pokemon's, making the fight balanced.
• [x] Balance shall be measured. For example, balance could means that the number of rounds needed to defeat the opponent should vary by only +/- <<3>> rounds (for example, if my Pokemon can defeat the NPC's Pokemon in 5 rounds, and the NPC's Pokemon can defeat mine in 7 rounds, this difference of 2 rounds is acceptable) OR the ratio shall be closed to 1 (for example, roundsForTrainerToWin / roundsForNPCToWin = 0.9 is acceptable).
• [x] If a perfectly matched NPC Pokemon isn't available due to limited resources, the system should provide the closest match possible.

Example of a mismatched case:

Here is an example of a mismatch we found while testing with the full JSON resource file.

[z-q-ying]

Update match up threshold from 2 to 1 in PR #142