Unlocking/Using smash balls in SSF2 beta

Solution 1:

As the other (deleted) answer said, they are gone temporarily during a big update. It seems to be so that they can have the update available while still working on some features.

Rather than keep you waiting until these things are fixed, please note that some minor features will remain disabled temporarily including:

• Final Smashes
• Gamepad support in the Browser version
• Online Arena Mode (Sandbag Soccer)
• Peril Roulette in Classic Mode
• Character-Specific Break the Targets
• ‘Trades’ between opposing attacks
• Accessorized costumes
• Misc. stage hazards (Green Hill Zone, etc.)

We promise to send out auto-updates to enable these features as soon as we get the issues ironed out.

Source: https://www.mcleodgaming.com/news

TBH I'm not sure why the other answer was deleted besides making it unclear that they were quoting the site.