What I mean is that they didn't centralize gameplay as much. Primes for the most part had barely any more HP and did just a bit more damage, while LEGENDS were almost unplayable, that's why I said to SOME extent for those sets. There were still gimmicks, but they weren't required to win.
I don't think you're remembering this time accurately. Pokémon Prime were
not a game mechanic in the truest sense, but were a card rarity (like Common, Uncommon, etc.). Pokémon Prime were a gimmick, however, because they were just
better versions of Pokémon from the traditional (Common, Uncommon, Rare, or Holo Rare) rarities. They had more HP but were
only worth a single Prize. It'd be like Buzzwole-GX being instead released as just another Buzzwole with "only" 150 HP and no-GX attack... in a cardpool where GX-attacks weren't a thing in the first place. @_@
They had better effects but
nothing punished you for running them. They were a
major part of the metagame during the short time they were legal; remember, Pokémon Prime and Pokémon LEGEND cards were only around for five sets (HeartGold SoulSilver through Call of Legends). There are 26 Pokémon Prime and the ones I
still remember because of how competitive they were in the Standard Format of the time (as opposed to Unlimited or Legacy Format decks) are Blissey, Donphan, Magnezone, and Yanmega. Let me
stress, I'm talking about the ones whose success I can explain with (at most) a cursory glance at the card.
Most actually had at least a niche, somewhat competitive deck, one where they were maybe a situational card or were quickly outclassed by another release later in the period.
Each Pokémon LEGEND card was made of two pieces, so while there were 18 total Pokémon LEGEND cards released, only nine actual Pokémon LEGEND exist. At least one (Rayquaza & Deoxys LEGEND) saw some competitive success, added into already successful Emboar (BLW) based decks. One out of nine actually being competitive sounds like most of the cardpool, maybe a bit low for the spotlighted gimmick.
If you want this back... all right, but it's basically Pokémon-GX without the GX-Rule or GX-attack... but the same GX-rarity (and monetary cost)!