Also, to add, Pokémon could also use a real mulligan rule (like Magic) so if you get a bad hand you can shuffle and redraw 1 less card even if your hand has Pokémon in it. Furthermore, like someone said above, you should have 15-card sideboards (like Magic) for competitive play, so you don't have to include specific anti-deck tech just on the chance of facing a deck of that type.
The trifecta of no mulligan, no sideboard, and prize cards instead of a KO counter makes Pokémon TCG the most luck-based TCG out there, and easy to tell why Magic: the Gathering is the biggest TCG with the most proper competition.
You can't make the same mulligan rules on the same TCG as it have different mechanics. On Pokemon TCG, you can't start a game without a basic pokemon, and applying that mulligan rule from MTG will make games unplayable for that player.
The sideboard thing though, is the one I will agree.