I would say as long as you can get the same or very similar feeling in weight-assisted practice as in solo weight-free exercise, you're good.
IMO it's about transforming the body to such a state that only Jin is being used. All the Li needs to be converted to Jin. Once it's done you can't really move in a 'wrong' way without consciously trying and struggling - even then, it may not be possible anymore.
When you add chocolate to a neutral ice cream base it's hard to say that it's the same as vanilla just cause the texture or base flavor is the same.
Popular tools are:
- regular bodyweight only Jibengung
-> which for me seems enough. Include dragon squat, hand stand walking and pushups, one armed stuff. All done with the same feeling of Sung and building Jin. Even more: jump work, Saltos, flying kicks, turning and spinning stuff.
How to train pulling? Fa Jin is strength training if done properly... Add compression for the bones and circular movement for joints...
I still have a lot of work to do in that direction
Small 0,5 to 1,5kg wooden clubs, ball and spheres of various sizes, pole shaking, weapons training.
Don't forget just going for a swim or run with some internal awareness. Or a lot, depending on how and what you want to train
Diving, Pranayama, construction work,...manual labor. Or moving people around like I did as a nurse for the elderly. That was excellent push hands.
Mark Ramus likes bouncy stuff. Big gymnastics ball, rebounder or trampoline. Adam says to give up all external training - which I would say is just saying do only that which helps convert Li into Jin. Mikhail says to let go of all tension, to find a configuration of the body that allows for no tension in all parts of it - that means it includes both sinking and rising in one system. My own teachers say to keep yourself stretched between Heaven and Earth throughout the day, but the two have radically different body structure and application style.
Equipment filled with water is also cool. Or doing Sung training in actual bodies of water. Riding the bicycle also counts...
It's the feeling first that's important. Obviously struggling, effort, muscle failure, sweat, etc are part of traditional training. If you can't maintain correct internal feeling during strenuous solo training, forget about application.
But when all you do internally is tense up and squeeze that's all you're going to get. Not bad and can take you far, but then why train IMA if the end result would be the same as going to the gym?