Do you feel that you have an easy time punching flips?
I'm still getting used to the terminology after my ~30 years out of the game. By 'flip' i think that's the same as 'flick' or ages ago the term i learned it as, 'pick' ... if so, most if not all flips have no downspin... if the flip is not too close the the net and/or very low, i can generally punch it where i want to.
0:00 - 0:03 - after a rocket serve, i punched to J's FH.
0:05 - 0:09 - I see J lean to his FH (we were drilling my rocket serve and punch to his FH), my subconscious brain/muscle memory overrode my conscious brain and punched it to his BH
0:42 - 0:46 - camera facing me, you can see my 3rd ball punch to J's FH after the rocket serve.
With all that said, I'm at a certain level with my punches... i generally cannot punch downspin balls. At my old club, I've played another oldschool penholder and he can punch downspin balls. It's a matter of blade angle and I can't get it consistently yet, so for my current game, i play the safer 'push' back.
Joke Interlude:
Patient: *raises elbow* "Doctor, it hurts when I do this."
Doctor: "Then don't do that."
My advice is to not give him punchable balls. Learn serve receive (says the 500 serve receiver, i'm da suck at serve receive). There's something in his brain/game telling him to step around to return your serve with his FH instead of punching. If his punches are giving you that much challenges, how are you returning those serves that makes him step around?
What kind of serves or 2nd balls are you giving him to punch?
Can he punch downspin? IMO, that's a higher level skill. If he cannot then, learn to 'push' (add downspin) back his serves. Or learn to place the ball short in his FH or middle of the table. Or learn to read topspin ... etc.
my biggest problem is dealing with his punches. I know they should be weak shots relatively, but his speed and placement are good, and he doesn't actually telegraph exactly where it's gonna go, he can change direction sometimes.
Not sure of your partner, but in the video posted above, my punches are not weak IMO. You can see I can change direction also.
You mention your partner punches HARD, but then you say you know punches are weak shots relatively. Deal with Reality and not Fantasy. Accept he punches hard and deal with it accordingly. Don't Deny what is happening even if it doesn't fit in with your Knowledge.
After having said all that, even a weak punch (or any weak shot) is 'strong' if the placement is correct. Generally place the ball where your partner is not ... sometimes you will see magic happen!
I think my best bet is to improve my flip against his backhand or maybe actually play a push. Aside from just adapting to the shots and getting better in general. What do you think?
My advice is to try everything and anything when your shots/returns doesn't work. You have to find what works within your toolbox/arsenal.
Truly HTH. Good luck in your Training!