To verify. I recall:

Beast Wars Neo Cohrada

Beast Machines Nightviper

Earthrise Slitherfang

WFC Fangtron (Slitherfang redeco)

I think I am missing one in Arms Micron.

 

You are. It turns into a cobra
Gob (Prime) - Transformers Wiki

 

Fuzor Quickstrike has snake parts. Not sure if that counts for your purposes.

 

I think that counts somehow. Thanks!

 

If you wanna get silly, there's the TFCC Serpentor crossover fig.

 

He doesn't transform but

Kreo Corhada

 

Are you just counting unique molds or different releases? Asking only because the Telemocha Cohrada was quite different in terms of color compared to the Neo release.

 

 
There are a lot of snakes in the Decepticon camp!  

 

Squeezeplay has a snake head.

 

Good call. Noted together with Quickstrike.

 

Hadn't heard of this one before! Thanks!

 

Also, I just remembered that in the Spanish dub of Beast Wars he was renamed simply as "Cobra"

 

Oh cool I had forgotten about that variant. Thanks!

 

DotM Darksteel is decoed as an homage to Quickstrike, including a snake head.

 

And there are 3 color variants! Thanks!

 

Tfwiki actually has a page for lists of all characters with certain beast modes right here