That “surprise” came via Dragon Ball Daima when the newest version of “Kid Goku” unlocked a “non-canon” power via Super Saiyan 4. This form had been locked in purgatory for a long time ...

Dragon Ball Daima Episode 20 finally revealed how Goku achieved Super Saiyan 4, but the explanation contradicts previous ...

For example, Kid Goku will cover all series that use that form. Oozaru will be omitted, just because Goku's Great Ape form is not unique. Still, it is a simple but great design.