I understand that normally, a Super Sentai team would have 6 rangers but can Super Sentai teams have 7 or 9 rangers?

Go-ongers/Rpm had 7, and Kyoryuger had 10, so yes. I forget the exact number in Dekaranger/SPD, but it was around 7 to 9 as well.

Kyoryuger had 11 with Deathryuger and Dekaranger was 10, while SPD was 9.

Is this counting Gold?

It has to, since the only ranger in Dekaranger to not appear in SPD is the (Incredibly brief) transformed Marigold.

Also, if you're counting Deathryuger for Kyoryuger's count, shouldn't you count SPD A-Team, too?

So they used Swan? I missed a lot of SPD.

Yep. DekaSwan was renamed SPD Kat Ranger, while DekaBright was SPD Nova Ranger.
Only Marigold was absent.

Also, you should check out SPD. It's not the best, but it's a pretty good PR season.

I caught the final battle of SPD. I saw Dekabright/Nova Ranger for the last few seconds. Did she appear anywhere before that?

Nope. Nova Ranger only had one appearance.
Though, to be completely fair, Dekabright only had one appearance, too. So not much footage of her was around, anyway.
Same for Kat Ranger and Dekaswan. One transformation.

I knew Dekaswan was only one shot. Yet she appears in the legendary battle in Gokaiger.