Unlocking Event Characters at Certain Levels Only?

No you can unlock them by colecting event points

Fart

You are only able to unlock event characters by reaching a certain number of Event Assessment Points!

Each duel against the character gives you Assessment points.

The Assessment points are than multiplied by an event multiplier!

The event multiplier is based on the level you dueled against!

Level 10, 20, 30, 40, & 50 give different event multipliers!

The higher the level you face.
The higher the event multiplier.

Once the calculation are done.
Your new Event Assessment Points are stored & will accumulate every time you duel against them.

Once, you reach enough points you unlock prizes + the character.

You could theoretically unlock the character by dueling against the easy level 10 version.

However, most people go for the higher ones to get better drops + faster points.

you unlock them by getting a certain number of points in the event. it doesn't matter what lvl you beat them.