Why would you ever use Withdraw over Bubble on Squirtle (Base Set)?
Base Set Squirtle has two attacks:
Bubble, with one Water Energy. Flip a coin. If heads, the defending Pokémon is now Paralysed. Deals 10 damage.
Withdraw, with one Water and one Colourless Energy. Flip a coin. If heads, Squirtle is immune to all damage during the opponent's next turn, but other effects still apply.
But if the opponent is paralysed, they won't be doing any damage or any other effect to Squirtle on the next turn anyway (unless they heal off their paralysis via Full Heal or evolving—though your opponent could just as easily Gust of Wind your Squirtle to your bench and then Withdraw is useless). Plus, Bubble actually makes progress since it deals damage. And Bubble and Withdraw have the same success rate of 50% (but the 10 damage from Bubble is guaranteed).
In what gameplay scenario would one ever pick Withdraw? It even takes more Energy to use.