The dumpster dive for free agents
Considering that Troy Weaver has done nothing but add busts and "flyers" over the last three seasons, these two players are probably the most realistic options.
Pokusevski is the type of high-ceiling, unsuccessful player that Weaver loves. He is a seven-footer who should be able to block shots and shoot but so far in his career he hasn't been able to stay on the court. If this is the Pistons' big move in free agency they may as well pack it up for the next decade, though I would take him on a two-way or minimum deal if the Pistons have an open roster spot to fill. He did average 1.3 blocks in 20 minutes per game last season but was only able to stay healthy for 34 games.
If you were hoping to get another Isaiah Stewart, only worse, I have some good news for you! Achiuwa will be a restricted free agent, though it's hard to see the Raptors fighting too hard to keep him. He's a middling, tweener big who can't shoot, so I can't see the Pistons being that interested, though I do love his toughness.