This zombie can be very dangerous to your opponent for the relatively low cost of 3 brains. It is best played on lanes unoccupied with plants to make use of its Anti-Hero trait, where it can attack your opponent for 6 damage instead of 2. However, your opponent will not leave it on its own and will attempt to block it if they predict your play, and Stealthy Imp's stats are not good enough to last it through a single turn of combat against most plants. Thus, it may be better to play it a bit later so that you can assist Stealthy Imp with cards such as Backyard Bounce, Smoke Bomb, and Pogo Bouncer so that it can attack on an empty lane safely.
As Super Brainz, playing Carried Away on Stealthy Imp and moving it to the right can allow it to do 12 damage to your opponent in one turn, or even 18 if it has already attacked your opponent before Super Brainz blocks and gets the superpower. This serves as a nice early finishing move, and is especially effective against opponents who have not set their defenses well. However, make sure that your opponent's Super-Block Meter has more than 4 empty bars, or else they may block one of the attacks. Also, this combo is countered hard by Wing-Nut, so remove any Wing-Nuts on the field before you execute this combo.
Since Stealthy Imp is an Imp, Toxic Waste Imp allows Stealthy Imp to destroy any plant in its way, while Imp Commander allows you to draw cards while Stealthy Imp does massive damage to your opponent. It also has access to pirate synergy with Captain Flameface and Swashbuckler Zombie, the former (positively) interacting with not only Swashbuckler Zombie, but also Toxic Waste Imp and Imp Commander. However, do note that even if it has gained the Strikethrough trait, Stealthy Imp's Anti-Hero trait will not activate if there is a plant on its lane. Also, since it has the Gravestone trait, you can also make use of Headstone Carver to give it a slight starting boost.
Against
While Stealthy Imp can hit very hard, this zombie does not pose much of a threat without its Anti-Hero trait active due to its low base stats, and any plant with 2 or more strength can take it out with no problem. But because of this, your opponent will rarely play it on his own, so expect it to be used in conjunction with support cards like Smoke Bomb and Backyard Bounce. In that case, plants with Team-Up can minimize the harm done by Bouncing cards, while covering as many lanes as possible will lessen the effectiveness of moving this zombie. If you have no option but to leave a lane uncovered, sacrifice the rightmost lane on the field. Also, remove any synergy zombies on the field, as all four of them increase Stealthy Imp's threat level significantly.
Gallery
Plants vs. Zombies Wiki has a gallery for Stealthy Imp.
Sneaky class. It costs 3
to play and has 2
/2
. It has the Gravestone and 
Anti-Hero 4 traits and does not have any abilities. Its closest plant counterpart is Poison Ivy.
Anti-Hero 4
Strikethrough trait, Stealthy Imp's 
Brainy
Crazy
Hearty
Sneaky
