it is not stated that apollo is an antagonist.
The question is, what is the plot of Child's Play? A plot requires a protagonist (but I know that you mean "good person" by "protagonist") attempting to reach a goal, and an antagonist to stop the protagonist. Personally, I believe Ian is the protagonist, but without a clear plot, it's impossible to really determine who the antagonist is. Cool Boi and I have discussed this before, but the plot we determined sounded more like a summary than an actual plot.
On the topic of Apollo, I predict that he's going to go against Ian at some point of the story, but however it turns out, I doubt he will be considered the antagonist.