Fire / Ghost
Not exactly sure of the nuances between regular CAP and this project, but if we're allowed to make some polljumpy reasonings that's fine with me given the limited toolset of Gen 1.
The idea here is that Fire Blast is a pretty strong Special move, especially with STAB, but its chance to Burn is a mixed bag. On one hand, Burns are quite good against a variety of Pokemon, namely Physical/Mixed Attackers (or just exploders) that don't commonly run Rest like Tauros, Rhydon, Dracolilla, Exeggutor, Cloyster, and Gengar. Still, forcing a Rest can be useful for dealing with something like Snorlax. On other Pokemon, however, you may prefer them to be targets of Sleep, Paralysis, or Freeze, but with Fire Blast being your main STAB, an accidental Burn can get in the way. Herein enters Haze, which can let you remove Burn from something if you'd rather leave them vulnerable to another status, along with any other useful utility Haze already has.
Fire/Ghost is a cool typing that improves our match-up into Snorlax and Tauros, the most common physical mons in the metagame, but the common Earthquake remains an issue, and not resisting Ice this gen sucks as well. So Fire being mediocre defensively and Ghost being really good defensively balances out into a solid type overall, with good utility but some pretty obvious weaknesses, which is nice considering our primary targets.
Having more Fire moves in the metagame sounds nice too considering Freeze is so powerful. More chances to thaw yourself, or to bait in a Frozen mon. Win/Win honestly.
I don't think a fire blast offensive mom would want to run Haze unless it has a SEVERE 4mss, right? Like, yeah accidentally burning a Chansey is terrible but we feel like you'd prefer running physical coverage vs Chansey rather than Haze, no'?