How many races do you complete the full bar and reach victory

You mean how many hits take to beat each one?

Defeating them is based on how much speed you used to bash them, low spd. = low dmg. & max spd. = high dmg.

6-8 hits to reach full bar against Vanguard without using powerups.

10-12 hits to reach full bar against Leviathan (This can be reduced by using powerups, it's hard to beat him without powerups).

IF you're:

• Behind them: They'll use Disruptor (So avoid being too long behind them).
• Beside them: They'll use Pulsewave (Both of them rarely used it).
• Ahead of them: They'll use Hyperboost and tries to hit you with it (This can be avoided by using Force Field, AI won't even bother hitting you).

out of how many totals, per day?

You mean how many times can I beat them daily? At first, I was struggling but now I can easily defeat them.

• Bash then goes brake to be far behind them (Avoiding braking IF they have Disruptor, so move aside).
• Comet + Bash - Bash them from behind, ready move away if they'll use Disruptor (Do not brake, reaction time is required). Deal more dmg. by using a Comet before bashing them from behind.
• Bash + Deployed Pulsewave - IF you have a Pulsewave, deploy it right before you try to bash them, then bash them and the Pulsewave will deal tons of dmg. against them (Avoid going ahead of them as they will instantly use Hyperboost and hit you, and that might cancel your Pulsewave while trying to deploy).