I’m going to try and give you some unprejudiced advice
Have you got experience with Evolve products? If not I would do a whole bunch of reading on the brand before deciding on any purchase.
If the board is new make sure the warranty is unaffected by transfer of ownership and ask clearly why the board is being sold via email so that you have evidence of the answer. The reason I say this is because you will find a lot of Evolve boards on the market practically new, this is due to Evolve’s super complicated and in many markets borderline illegal returns policies. They make it extremely difficult to return a faulty board and so buyers just give up and sell it on privately.
If the board is old I would ask the seller if all of the enclosure screws are intact, they tend to vibrate out on bamboo models, ask what parts have been replaced by Evolve and if and what issues it had on first purchase.
Ask them to inspect the motor mount brackets for hairline cracks, this is a big issue with the bamboo series as well and will eventually lead to a break.
Ask if the motors become too hot to touch after a ride, if the belt tension on these boards is even slightly too tight it will destroy the stock motors, they get really hot and eventually die, it can happen in a matter of hours.
Ask about battery sag, how far can the board go before sag kicks in and the ESC chucks the board into Eco mode, this can be anything from 3 miles to 10 miles on a bamboo GT (not GTX) and becomes a huge issue when the battery has been cycled 50+ times - which isn’t that much!
Ask if the board has a R1 or R2 remote and if the remote connection is reliable, connection dropouts are no joke and are absolutely rampant with Evolve.
That’s all I can think of right now. I’m sure there’s loads more but this will cover the basics.