Once per turn, during your Main Phase: You can Fusion Summon 1 Machine Fusion Monster from your Extra Deck, using monsters from your hand and/or field as material
Thats a very good effect, especially for decks like Charizard ex which have high retreat costs and otherwise cant justify burning energy on retreating, but it has another effect if you read between the lines
With so many small creatures, having something like The Royal Scions to give them a bit of extra punch is a big deal
Nothing comes to mind I think this just isnt a card meant for Legacy outside of a Soldier Stompy shell (if that)
Do not use polish anything with a third layer of holographic accents, such as repeating patterns and extra embellishments like the cards above
Your best bet is to take a Prize lead, try to maintain it by targetting Gardevoir ex as soon as it comes down (keep your Cross Switcher for it), and using Morpeko to revenge KO Gardevoir in the late game, in combination with Iono