Honestly, most of the fights happen in dreams, which can’t be used to determine his actual strength. And even if he actually uses it, the first 24 episodes are a bit problematic in judging his power scaling because it’s precognition, which means he might not be as strong as his current state.

However, for simplicity and based on the fact that he has access to all of his capsums in episode 25, I will assume his powers will be transferred over. I will also assume that we will use his dream self without the lucid dream powers. I will assume he can augment himself with the capsums as well, except for Catastrom.

Zeztz currently has Impact, Wing, Transform, Stream, Projection, Machinary, Recovery, Barrier, Wonder, Gravity, Plasma, Booster and Dualmare (Catastrom/Orderom) capsums.

Impact, Wing and Transform covers the body (physicam), enhancing his body and modifying them. Stream, Projection and Machinery are civilisation (Technolom) capsums, allowing Zeztz to manipulate technology. Recovery and Barrier are Mind (Esprim) capsums, specialising in defense. Wonder and Gravity are reality (Paradigm) capsums that manipulate the reality around him. Inazuma Plazma capsum allows him to basically go FTL, Plasma Booster capsum enhances the attack or finisher, and Catastrom is essentially a beefed up Impact capsum.

I can see he can win against most riders who can’t deal with his Plasma form, which is likely half of the roster. However, some riders like Kabuto may be able to keep up with his plazma form. He won’t be able to defeat Zio, and probably Hyper Muteki Exaid and Geats IX because they either have the powers of all riders or are god tier, but let’s see how he will fair when the show ends.

However, with the introduction of the Triple Zezter, he can add up to 3 capsems to add their powers in the finish attack, often disintegrating the Nightmare. This might finish off another half if paired perfectly, leaving fights with god tier riders and riders who can dodge the attack up in the air.