All Subs are compatible with the Arc. I do think the Sub mini would be a bit underwhelming with the Arc.

All S2 capable speakers are compatible with the Arc. If you want to use them as surrounds, the Roam and the Move cannot be used as such. Se Sonos app version compatibility | Sonos for the S2 capable speakers.

Although all Subs and the Sub Mini are compatible with Arc Ultra, if you wanted to dual sub then you would require either two Sub (Gen 3) or two Sub 4, or one of each.

There are also restrictions over what surround speakers can be used with Arc Ultra. For instance, Play:1 and Play:3 are not compatible (assuming Sonos have fixed the bug that initially allowed them to be used). For surround compatibility see https://support.sonos.com/en-gb/article/surround-sound-guidelines-and-limitations?product=arc-ultra

Isn’t all this information detailed in the FAQ on the Arc Ultra’s sales page at www.sonos.com?