He could proceed to have a bunch of bots throw coins around randomly, also, so trading volume gives you nil reliable info, either.
This sort of behavior only works on exchanges with zero or extremely low trading fees.
The trading fees would merely have to be lower than the appreciation in the value of your own holdings as a result of the apparent legitimacy.
At 0.05% fee (public rate for Binance, is probably lower for people in the know), it is a four-figure USD investment to get your coin in the top 100 volume chart for a day. Then when real people start buying in, you can sell a tiny fraction of your holdings to finance more fake volume.
It also works when you own the exchange. There's pretty good reason to believe wash trading is happening at several exchanges...possibly performed by the exchange themselves. I'm more willing to believe Bitfinex is doing the BTC wash trading that's happening on their exchange, rather than some whale doing it (the very close connection between Tether and Bitfinex, sharing several founders and C-levels, makes this seem even more likely).
Volume is just as gamable with a bit more effort. One person can create $1B volume by moving $1M between two coins 1000 times. And consider that $1M could be inflated by a major creator/miner of the coin as discussed above. Get yourself up the volume and market cap charts with this inflation and people outside the scam will buy in. There you go, the basic anatomy of a pump and dump.