[Phantasm]

I prefer to build symbiotes and battlesuits as Alternate Forms rather than as Allies.

For a battlesuit example, Jarvis and later Friday would be the AI Allies who assist Tony in managing the suit rather than the suit itself; the suit would be an Alternate Form of Tony's (with Projection and Selectivity as options for the Mark 42 in the MCU).

A Venom style symbiote could probably go either way, though, depending on time frame. Depends on if the symbiote maintains a personality separate from and can consciously go against the host (say, leaving Eddie in an attempt to go back to Pete) or if the two merge to become someone new with personality traits from both. In the case of the symbiote maintaining a personality and conversing with the host, if the host is the one in control then the symbiote's personality is likely a "Spirit"/"AI" type Ally.

tl;dr: "Depends on if the Ally is the one in complete control of the powers."