You are only allowed to view your sideboard in between games, or when a card makes you search your sideboard, such as [c]Cunning Wish[/c]
(Iona, Shield of Emeria is no longer commander legal, however, at one point in time she was legal and at this point I'm too attached to her being a part of the deck to remove her
While the cards come in different rarities, often related to how strong they are in play, you can make capable decks with cards of any rarity
There's also some good Golgari ways to get creatures into your yard and so this is an okay enabler/payoff
In your case, Lucario- EX is Basic, M Lucario- EX is Mega evolution that "Evolves from Lucario- EX " so you only need Lucario- EX in play to be able to evolve to M Lucario- EX , any other combination won't work [1]
What affects the value of Soul Pocus