I'd argue that the challenge is where the satisfaction comes from.
Sorry but this kind of analysis is getting old (and it's annoying when people repeat that same rhetoric).
The difference is that in that franchise's universe pokémons are actually thriving from fighting since they're not like normal animals. Also they don't die, even a powerful attack only knocks them out.
View attachment 33203
It's kinda argue that some games are hard not because of the challenge but because they're badly balanced.
Spelunker on the NES or Superman 64 are both hard games but not in the good way.