Most DH bikes will work with external routed dropper.

Do Hardtails have dropper posts?

It's the same for full suspension bikes; but even on the most humble of hardtails a dropper post will increase your control of the bike exponentially. ... Check out our range of droppers here, and if you have any questions about fitting it to your bike, just ask!

Can you use a downhill bike for trails?

Riding a heavier downhill bike on hills and trails is tough because it wasn't built for it. It takes a lot out of you, but it can be done. The best bet is to pick up an enduro bike and you can do all of the downhill and XC trails you want and enjoy it the whole time.