Suggestions on transferring fish to new tank

I recently purchased a bigger aquarium and i want to put the fish I have in my current tank into the new one. I'm not going to use the sand from my existing aquarium and I'm going with PFS. Since I'm changing the substrate do I still need to "cycle" the tank? I'll probably use the same filters for a little while as well.

I would fill it and give the water a few days to settle. Then swap over the fish and the filter together!
If you want to setup a new filtration system do it before you add the fish. You could always seed the new filtration system with the old filters but if you are not going to use the old aquarium then there is no reason to not use the filters.

Adding new substrate won't really matter. Some bacteria live in the substrate but the vast majority are going to be in the filter.

As long as you swap over the filters and fish at the same time you will be fine. If you later want to add another filter leave both filters setup in the tank for a few weeks and the old one will help jump start the fresh filter.

That makes sense. I'm planning on getting a used canister filter from someone this weekend, he said it's already seeded. Would it be safe to use that filter as well or should I replace all the media and seed it myself? I plan on using this smaller aquarium as a grow out tank so it will still need the filters. I'm currently using a fluval 205 and a small penguin biowheel on a 30 gallon.

If it is already seeded the only concern would be what his bio load is. If yours is much greater it would likely cause a spike of ammonia/nitrite while the filter catches up.

You could leave all the filter setup on the big tank and then when you are ready to use the smaller as a grow out take the one filter off the larger and move it back to the small. That way they all stay cycled and will only need small adjustments for bio load.

He said its being used as a spare on his 120g, ill be putting it in a 55g with about 12 fish at 2 in.

I don't really see that being an issue just have to keep an eye on the ammonia and nitrite levels for the first two weeks. Might see a small spike but as long as it has been up and ready I don't really a problem haha.