Air Balloon attaches to a Pokémon to make retreating less costly, reducing 2 Colorless Energy from its Retreat Cost. The two wordings describe the identical reduction, with Black Bolt simply switching from writing out 'ColorlessColorless' to the standard bracketed symbol notation used in modern printed text.
Air Balloon first appeared in Sword and Shield in 2020 with art by Yoshinobu Saito, who also illustrated a Secret Rare treatment in that same set. Studio Bora Inc. illustrated the Black Bolt printing in the Scarlet and Violet era and the Mega Evolution era printings in Mega Evolution and Ascended Heroes, the former an Ultra Rare treatment, carrying the card through five printings in four sets. Its two higher-rarity printings, the Sword and Shield Secret Rare and the Mega Evolution Ultra Rare, come one from each illustrator, and more than five years passed between the Sword and Shield debut and the Black Bolt return.
The Air Balloon is a held item in the Pokémon games that prevents the holder from being damaged by Ground-type moves. On the card, it instead lowers Retreat Cost, by the same 2 Colorless Energy in every printing, and it has stayed an Uncommon in its regular Sword and Shield, Black Bolt and Ascended Heroes printings.
Sword and Shield printing is Air Balloon's first appearance, illustrated by Yoshinobu Saito
Sword and Shield printing also includes a Secret Rare treatment
Mega Evolution printing includes an Ultra Rare treatment
No, both wordings describe the same 2 Colorless Energy Retreat Cost reduction; only notation changed.
It is a held item that prevents the holder from being damaged by Ground-type moves.
Yes, in the Mega Evolution era's Mega Evolution set.
From Sword & Shield (2020) · 2 printings
The Retreat Cost of the Pokémon this card is attached to is ColorlessColorless less.
From Black Bolt (2025) · 3 printings
The Retreat Cost of the Pokémon this card is attached to is {C}{C} less.

Air Balloon
Pokémon Tool
First printed in Sword & Shield (2020)
The Retreat Cost of the Pokémon this card is attached to is {C}{C} less.