They are probably, and likely always will be, the most consistent and constant thing about the Pokmon Trading Card Game
This might be due to a spell or ability resolving, a permanent you control entering the battlefield with counters, or combat damage from a source with toxic, infect, or wither
The effect stops Raya, Leader of Heart from receiving any damage when she challenges a damaged character - making the card a great way to pick off cards left smarting by your other challenges or card effects
The price tag slapped on these cards is based on the valuation given by tcgplayer.com and cardmarket.com, and is subject to change depending on several conditions, such as availability, rareness, and relevance in the meta
Instead, it took full advantage of the videogame franchise it was developing alongside its trading card game