If my partner is 36 years old, financially able to afford at least $300k resale, should we pool together to buy a condo or buy separate properties each (ie. resale for him, and 1BR condo for me)?

Between the 2 options, option 1 is more sensible. There's no guarantee you will be able to flip it after 3 years for a profit, and the next condo you find may be much more expensive than what you anticipate..Transactional fees eg. stamp duties and all will also eat into your potential profits.

But have you thought of this...

Is a condo truly an upgrade over a resale HDB? You may find that if you don't use the facilities you end up having a downgrade in terms of location and space.

Also do consider that financing for a second property may be difficult in terms of the downpayment and maximum bank loan available in one person's name.

Lastly HDB does have specific rules in terms of inheritance in the event of one partner's demise. If it is not joint owner the person inheriting the HDB might have to sell the HDB upon inheriting it or sell the condo and move to the HDB.

Go for option 1 to stay.

But size it right such that he is able to buy at least a 4 room flat so that you do not need to move to a bigger flat if you guys have kids.

Concurrently buy a condo under your own name. Preferably New Launch so that you can see bigger capital appreciation nearing TOP.

Once reach TOP, Review your plans again.

If you need a bigger unit, see if you guys want a bigger flat or not?

If not continue stay in the 4 room flat.