The main part of madolche is consistency. The deck is capable to break board going second. It can also build a decent board going first.
However, the main issue with madolche is consistency. Therefore, pot of prosperity is important. If pot of prosperity is too expensive, pot of extravagance can replace however it is way less good since madolche do not need the extra card. They need the key card. The second card is small world. It allows to search mageline, angelly or petite through hand traps which are all key starters of the combo.
ex of small world: ash blossom -> hootcake -> and lvl4 madolche, or ghost bell -> veiler -> mageline
Having different hand trap for small world is also in synergy with crossout.
depending on the handtrap that you have there are multiple different ways to search the card through small world. If both previously mentioned cards are too expensive, you can choose to play a more going second version which drops all hand trap, pot, and small world (I admit that they are expensive) and adds cards which break boards such as dark ruler, harpie, kaiju, nibiru, and raigeki (back at 3 with the jan 2022 banlist).
In this deck, there is no side deck because it really depends on the format.
I do suggest cards like dark ruler, dimension shifter, lancea, droll. Regardless of what you choose, I suggest choosing cards that either has a board wipe or influence the entire board effect such as dark ruler or card that apply a rule such as droll, lancea which denie your opponent from one type of effect.
If cards like lightning storm aren't accessible and you need back role removal. Hey Tsunade is a decent choice. Since you do not need multiple turns as madolche player. 1 Turn is often enough.
Personally, the key card that wins me most of my duels is madolche teacher glassoufle. The shuffle-back effect from both gy is a really annoying effect for current format decks. The hard part is to know when to activate it. You have to do it 1 step before your opponent's foolish-like effect. Not 2 steps just 1 in order to trigger glassoufle's effect in the next chainlink.
Reglardless, Madolche is a deck that have a lot of potential. It is not hard to learn the combo and fun deck.