Parents: Sableye + Lopunny
Shared Egg Group: Human-Like
Offspring Name: Loppeye the Sailor Man
New Typing: Ghost/Normal
Base Stats: 67/85/89/69/91/87 [BST: 488]
New Ability and Desc: Stall + Cute Charm = Late Bloomer: Has a 30% chance of infatuating the opponent at the end of its turn if it moves last.
Notable Moves: Hyper Voice, Return, Shadow Ball, Shadow Sneak, Shadow Claw, Knock Off, Sucker Punch, Circle Throw, Power-Up Punch, Counter, Mirror Coat, Recover, Healing Wish, Heal Bell, Will-o-Wisp, Thunder Wave, Toxic, Calm Mind, Nasty Plot, Taunt, Encore, Magic Coat, Trick/Switcheroo
Role Identification: The bad news is that, on its own, Loppeye is a rather mediocre fusion. Its best bet is going the support route, and it does have a few things going for it in that regard, namely a wide support movepool, pretty decent speed, and a good defensive type. However, its ability is reliant on it going second, and its bulk is average at best.
The good news is that it has not one but two mega evolutions that let it fill two very distinct roles!
Parents: [MEGA]
Shared Egg Group: [MEGA]
Offspring Name: Mega Loppeye X
New Typing: Ghost/Normal
Base Stats: 67/95/139/89/141/57 [BST: 588]
New Ability and Desc: Late Bloomer --> Magic Bounce
Notable Moves: Fake Out, Hyper Voice, Return, Shadow Ball, Shadow Sneak, Shadow Claw, Night Shade, Knock Off, Foul Play, Snarl, Circle Throw, Power-Up Punch, Ice Beam, Thunderbolt, Grass Knot, Power Gem, Counter, Mirror Coat, Metal Burst, Recover, Healing Wish, Heal Bell, Will-o-Wisp, Thunder Wave, Toxic, Calm Mind, Cosmic Power, Nasty Plot, Taunt, Encore, Baton Pass
Role Identification: Functions largely the same as Mega Sableye, though it boasts even better defenses, an arguably just-as-good defensive typing, and far better speed. Sure, it's still pretty slow, but 57 isn't that bad for a defensive mon.
Furthermore, it also gets an impressive set of defensive/support options from its other parent, including Healing Wish, Encore, Thunder Wave, Circle Throw and Mirror Coat. It should be noted that it gets both Counter and Mirror Coat, plus reliable recovery on top of that, so it's capable of using those moves more than once over the course of the battle.
So that's if you want to go defensive. If you want to go offensive...
Parents: [MEGA]
Shared Egg Group: [MEGA]
Offspring Name: Mega Loppeye Y
New Typing: Ghost/Fighting
Base Stats: 67/145/99/69/91/117 [BST: 588]
New Ability and Desc: Late Bloomer --> Scrappy
Notable Moves: Shadow Sneak, Shadow Claw, High Jump Kick, Drain Punch, Low Kick, Power-Up Punch, Knock Off, Sucker Punch, Elemental Punches, Recover, Iron Tail, Poison Jab, Zen Headbutt, Fake Out, Healing Wish, Will-o-Wisp, Thunder Wave, Toxic, Taunt, Encore, Baton Pass, Magic Coat
Role Identification: A very threatening offensive mon. Though not as fast as Mega Lopunny, it boasts a higher attack stat, and it has that dank Ghost/Fighting typing that everyone loves, plus STAB priority in the form of Shadow Sneak. If you want to play more conservatively, it also has reliable recovery, and more than a few support options, but you're generally going to want to play to its strengths and invest fully in attack and speed, enabling it to hit just about everything as fast and hard as possible.