For Rocky Helmet, the opponent would have to think very carefully if getting some early attacks would be worth putting their currently active Pokmon into one-hit knockout (OHKO) range, thus denying an easy way of just attacking your currently active Pokmon
Lets dive into the Undercity and see which of these cards is the best
Set Number: OP-11
2 Jolteon Star (Ultra Rare) $484.50 Jumping Into A New Stratosphere If you were impressed with Flareon, then one of the most valuable Jolteon cards ever will shock you, as this Electric-type Pokemon leaves Flareon in the dust
They draw a card at the same time, take a main phase at the same time, attack at the same time, and so on
This will hurt, especially if your opponent has a bench full of ex Pokmon, and even more so if theyve already burned through most of their search tools