There is no verified universal best stat. Start with the fighter's visible weakness or the clearest repeated match problem, train one related stat, and retest against comparable opposition before changing another variable.
Start from the visible weakness
The official game description confirms that fighters have strengths and weaknesses, but it does not map every weakness to a public formula. Use the current interface wording as the starting hypothesis, not as proof of the final result.
- Copy the weakness exactly as displayed.
- Record the relevant starting values.
- Choose one training action that appears related.
- Save the before-and-after state.
Use reported stat names carefully
Independent coverage currently reports Power, Dexterity, Endurance, Stamina, and Agility as training labels. Until a live tooltip or developer source explains each formula, those names should not be turned into precise damage, speed, health, or probability claims.
- Label the source of every stat definition.
- Prefer live interface text over a generic boxing interpretation.
- Start a new record when an update changes the interface.
Run a one-variable comparison
- Use the same fighter and record the same baseline.
- Change one training focus while keeping the budget similar.
- Choose the closest available opponent and match type.
- Repeat enough times to distinguish a pattern from one result.
When to change the focus
Change the training focus when the live interface shows the current bottleneck has improved, repeated comparable results show no useful change, or the next league or match requirement introduces a different documented need.
- Do not switch after every loss.
- Do not chase a hidden formula that the game does not show.
- Protect enough cash for the next visible progression requirement.
What would justify a public recommendation
- Dated screenshots of the starting and ending values.
- A clear update title and training cost.
- Several comparable match records.
- A limitation statement explaining where the result may not apply.
- Training strengths and weaknesses is part of the official game loop.
- The game is in Early Beta, so balancing can change.
- No official public source identifies one universal best stat.
- Complete formulas and hidden weightings remain unpublished.
Primary source: Official Coach a Fighter Roblox experience. Changing prices, requirements, rewards, and balance should be rechecked in the live game.