Even if the HP is scaled the same, there is the option of a double weakness (something we also used to see in the game to balance things out). Few of the double weak Pokemon were every problematic enough for universal counter to be needed... but at least one did exist!
Actually, more than one but it's the same Pokemon with tweaked effects:
Kecleon.
EX Sandstorm
EX Legend Maker
DP Rising Rivals
Three out of the four
Kecleon have effects that make this Colorless Basic Pokemon with Colorless Energy attacks an easy splash for just about any deck. The attacks may be flippy and not seem like much, but remember that the newest of these cards is from Rising Rivals. It was always printed with a solid amount of HP for a "plain" Basic Pokemon and the Energy-to-damage ratios were better then. Even now hitting for double Weakness would make it strong tech for many decks thanks to the abundance of Energy acceleration. The EX Sandstorm version would be the least useful since it would have to utilize the desired Basic Energy cards of the types it wished to mimic and if both coin flips for Double Slap were tails you did nada. The other two were easier to use to hit anything with double weakness for good damage: even the minimal 10 damage they did before Weakness would get doubled twice, and thus be 40 points for one energy. A single "heads" meant 120!
So since we are having fun speculating, just thought I'd point out that seemingly massive HP scores aren't necessarily going to be that massive. Even without double Weakness, you just need the Pokemon-EX to be weak to one of the current "power" Types... which right now we hit most of (thanks to big basics, but we still hit the Weakness). A hypothetical
Wailord EX, even as a Stage one with record breaking HP would either be a one or a two-hit KO for a
Zekrom... and since it would be non-Pokemon-EX versus Pokemon-EX for the prize swapping, a two-hit KO is fine.