Generaider is a deck that aim at controlling the field and dish out powerful blow once everything is cleared.
Vala, Seidhr of the Generaider Bosses and Loptr, Shadow of the Generaider Bosses are two of the most importants cards in the deck and are required to have any form of consistency. Generaider Boss Stage is the bread and butter of the deck, nothing can be achieve without having it on board, Mardel, Generaider Boss of Light and Generaider Boss Quest are here to bring it to the field.
Your ideal setup with this decklist would be to summon Laevatein, Generaider Boss of Shadows during your first turn with your field spell and a trap (ideally, Generaider Boss Room because it will protect your activated effect from being negated). Then, as soon as your opponent draw a card in its draw phase, you will be able to summon Harr, Generaider Boss of Storms to the field (He is a powerful Omni-Negate that can also force your opponent to send a monster from his field or hand to the graveyard).
Generaider will need tributing (they either ask for Generaider monster or for monster that have the same type as them) to activate most of their disruptive effect, Harr, Generaider Boss of Storms and Utgarda, Generaider Boss of Delusion will need 2, Laevatein, Generaider Boss of Shadows will need to tribute herself. Luckily, that's where our field spell comes in action again. If you summon a Generaider monster during your opponent turn, you will be able to fill your empty main monster zone with Generaider Token.
Laevatein, Generaider Boss of Shadows has a powerful effect, it can tribute itself to summon another Xyz Generaider monster (Jormungandr, Generaider Boss of Eternity) and then it let you attach as much card from any field or graveyard to it as Laevatein, Generaider Boss of Shadows had material.
Considering Generaider monsters are mostly level 9 monster, World Legacy Monstrosity is a must as it allow you to summon powerful Xyz (Infinitrack Earth Slicer) or Link monster (World Gears of Theurlogical Demiurgy) fast (and also one good may to summon Mardel, Generaider Boss of Light if you don't have it in hand).
As much as this deck loves to special summon their big bad monster, it's also a deck that loves to control and can play through Summon Limit, that's why I play it in the main deck. You can still use both effect of your field spell under Summon Limit which is more than enough once you are setup. This decklist can be improve with more handtrap or disruptive card (such as There Can Be Only One (be careful with this one, even if all Generaider have different type, all your token are fairy), Infinite Impermanence, Effect Veiler,...).
It is important to note that, as it is a deck with, almost only, level 9 monster, Generaider can brick. Your oppening hand could be 5 monster that can't be summoned. There should be enough tool to prevent this happening too much time but it cannot be fully prevented. It also struggle a lot playing second without more hand trap and fast board breaker.
Albaz the Ashen is also present here, as a one of (or more if needed) because Generaider can play without their normal summon (thanks to Vala and Monstrosity), and in case of going second, being able to summon it and bring Mirrorjade the Iceblade Dragon to the table really helped me in some situation. It might be stupid to have it only at once for a first duel, it can easily be replace by something else, it's more of a "i like it card" than anything.
Generaider has been my go-to deck for a while now, the addition of Vala, Seidhr of the Generaider Bosses and Laevatein, Generaider Boss of Shadows this year really helped make this deck way stronger than it uses to be and I've always had a blast playing it. I've tried it against some meta deck and, even if it's far from being one, Generaider will not go without a fight against them.
That's all for this deck, hope you have a blast trying it.