The release of the Neos support cards in the POTE set actually made Neos viable enough as a deck but still there wasn't enough consistency. Now in the new BROL set we get a very intersting card that helps boost consistency.
The main principle of the build is limiting the amount of bricks played and increasing consistency as much as possible.
This should explain many of the ratio choices. And without delay let's analyze some of them:
Elemental HERO Stratos: Now most people that bother with HEROes, know that Stratos is a mandatory 3off. Well they aren't wrong but limiting our copies of Stratos helps reducing our normal summon slots and increases our lets say "flex spot" for adding more consistency boost cards. Apart from that with the release of EN Shuffle we have one more way to go to Stratos if needed and thus we limit his copies.
Elemental HERO Shadow Mist: Shadow Mist is a classic 2off in Omni HERO decks. However, Neos decks have one more way apart from Foolish Burial or Vision HERO Vyon to mill Shadow Mist, that way being EN - Engage Neo-Space. Well in the Ishizu format Shadow Mist is really important since she's able to search Mask Change with her effect, so you may want to increase her copies. Keep in mind though, that the deck can get to work with even 1 copy.
Elemental HERO Spirit of Neos: In my opinion, this dude is the best card in the deck. He can search most of the cards we need for our combos (Neos Fusion, Instant Contact, Favorite Contact, Engage Neo-Space and EN Shuffle) and that's why he is at 3. This is also the reasoning behind the ratios of Neos Fusion, Instant Contact and Favorite Contact. Apart from that don't you guys worry when it comes to summon him, since Cross-Keeper, Engage Neo-Space and EN Shuffle exist.
Elemental HERO Brave Neos / Dark Neos / Grand Neos / Air Neos: The first 3 guys are targets for Neos Fusion since they let us mill Neos and a Neo-Spacian monster and use them as Favorite Contact fodder. Dark Neos more specifically is also a good target for Instant Contact since he can provide fodder for Mask Change and lead to Dark Law, or even negate some monster effect (with his own effect). Air Neos on the other hand exists in the extra deck as a finisher and he is summoned solely by Instant Contact (providing that Neos is on the field or in the GY)
Concerning the side deck, to be honest it's a really hard case. As you can see most of the deck consists of engine cards and thus siding is hard. All the choices, are cards that can help keep the meta decks in check. In general though keep in my mind that Bystial cards are the ones damaging HEROes more.
Anyways, I hope you enjoy playing the deck and as always we are open to suggestions on how to make the build better!