The regular deck monsters all are pretty good for increasing the consistency of the deck. The first three monsters are focused on bringing out material to use for XYZ summoning (and the second monster can also be used as a rank-up spell from the graveyard). The fourth monster, a reference to Don Thousand, is a hand trap that lets you search and place the field spell of the deck on either player's turn.

Note that this field spell is quite good. It restricts extra deck summons for both players by making it so that each player can only summon up to 2 extra deck monsters that aren't Number monsters per turn. (Will be effective at slowing down decks that aren't focused on Number cards and do a lot of extra deck summons, which is... a LOT of modern decks.) The field spell also searches for an umbral card on your turn, and deals 400 damage to each player at every player's end phase. Note: the Don Thousand card from earlier can be special summoned from the graveyard if you XYZ summon, and will protect you from any burn damage you apply to yourself, so in theory, you should only hurt your opponent like this.)

The normal magic spell is also for making summoning your XYZ monsters / bringing out XYZ material easier.

The trap is a negate + turns one of your opponent's monsters on the field or graveyard into xyz material for one of your xyz monsters (you can target ur own field or graveyard if you wish though), which is a great method of removal. Can also summon umbral monsters if you banish it from the graveyard. Its alright, just inherently nerfed by being a trap card lol. I do think turning a monster into XYZ material is one of the strongest methods of removal, though, which is great.

Idk if the boss monsters are quite strong enough to be particularly good in modern day on first glance? At least, the Vector-specific ones, since Barian Chaos Dragon looks quite strong (prevents opponent from searching cards, among other things). Shining Masquerade V seems to exist just to be overlayed upon (makes sense tho lol) and Umbral Magician V has a pretty faithful effect to the anime (during damage calculation, get the attack points of your enemy's monster +100, and if you destroy a monster by battle, halve your opponent's LP, + separate from that it has a pop). Which is nice, just not crazy imo. Umbrals are definitely not. Completely unplayable dogshit now though. And thats what matters to me. HOORAAAAAY!!!!!!!!!! (and if you have the funny Barians Dragon with you its actually pretty alright I think!!!! Not close to meta by any means probably, but a fun deck)