A few comments:

There’s another active thread about fenders. IMHO, they’re essential.

Second, specific to your query about a rain suit, if you ride a bike in the rain, you’re going to get wet. Your choice: rain or sweat. My experience with breathable fabrics like Gore-Tex®: they work for me if I’m standing motionless. My physiology: I sweat more abundantly than breathable fabrics seem to be able to handle. That’s me; YMMV.

I’d second recommending a cycling poncho, but a cycling poncho is useless unless your bike has fenders. A cycling poncho (as compared to a generic poncho) includes straps attached to the leading edge of the poncho that loop around your wrists: essential to keep the poncho where it belongs. Downside to a cycling poncho: it’s a sail. If you’re pedaling into a headwind, you won’t go anywhere fast, and a crosswind presents a new set of risks.

This is a thread about commuting. Drawing from my touring experience, cycling in rain for more than a few minutes and / or more than a few miles means I’m going to get wet. That said, in relatively calm air and for relatively brief commutes, fenders and a cycling poncho work for me.