DNA Donors: Regieleki / Ferrothorn
Fusion Name: Regithorn
New Types:
Base Stats: 77 / 97 / 110 / 77 / 83 / 110 [BST: 554] (+0 HP / +0 Atk / +20 Def / +0 SpA / +0 SpD / +0 Spe)
New Ability:
Electric Fence = (Transistor + Iron Barbs)
Ability Description: Pokemon making contact with this Pokemon or using an Electric-type attack lose 1/8 of their max HP.
Notable Moves:
Body Press, Knock Off,
Power Whip,
Rapid Spin, Supercell Slam,
Wild Charge...
Energy Ball,
Thunder Cage,
Volt Switch...
Iron Defense, Leech Seed, Light Screen, Reflect, Spikes, Stealth Rock, Swords Dance, Thunder Wave...
Intended Role: Fast Physical Wall, Hazard Setter, Screens Setter, Defensive Pivot
Role Justification: Decently fast wall with serviceable bulk and a typing that is serviceable against the prominent physical attackers of the tier, especially with Electric Fence alongside what seems to be an endless amount of utility (no, really). Bombirdus does not want to be using Knock Off so long as Regithorn is around, and with Regithorn's STAB Thunder Cage and fast enough to outspeed, its not comfortable taking it on head on either. Aside from that though this mon has a truck load of utility, from Knock Off itself, to hazard setting, to hazard removal, IronPress shenanigans, SD for a surprise physical set, and even screens setting due to its high speed. It circumvents its passivity with Thunder Cage which can continuously cripple mons per turn and bypasses its subpar offensive stats. Overall, a decent wall and glue that can perform a variety of roles. It also does pretty funny stuff against VSwitch spam by reducing Electric-type attackers' HP by 1/8. It does very well against Magnegiri, which is a plus.
Regithorn has some glaring weaknesses however that can't be ignored. For one, 77 SpA is still really poor, and with no way to boost it can easily devolve into passivity. In particular, Regithorn does pretty poorly into Grounds. Although its true that Regithorn can use a STAB Energy Ball, due to its 77 SpA it still won't even do that much damage, since Grounds are immune to Thunder Cage and thus don't have to worry about its chip damage, though Regithorn does have Body Press as an option with its defense stat and access to Iron Defense. Another problem is Regithorn's longevity, as it only has access to Leech Seed. Aside from that, it has to rely on Lefties (prone to Knock) or Giga Drain (75BP ontop of 77 SpA), which means its prone to being worn down throughout a game.
The following sets are just some of the examples of sets it can run, though if I'm being completely honest I have no idea how to build this mon lol. Its just got a lot it can do, and it doesn't require a lot of moveslots to do its job since Thunder Cage + Utility is almost all it needs and it leaves a few moveslots left, so its very flexible in that department. In that regard it can fit into a multitude of team playstyles and its moveset is very flexible to fit what it wants.
General 
Regithorn @ Leftovers
Ability: Electric Fence
EVs: 252 HP / 4 Def / 252 Spe
Timid Nature
- Thunder Cage
- Spikes / Stealth Rock
- Body Press / Rapid Spin
- Volt Switch
Standard Regithorn set. You've got your choice of whichever hazard you prefer and a combination of Thunder Cage and Volt Switch and either Rapid Spin or Body Press, depending on if you don't want to walled by steels or want Regithorn to act as the team's resident spinner. Due to Regithorn's speed it acts as a very solid hazard lead.
Mixed 
Regithorn @ Leftovers
Ability: Electric Fence
EVs: 252 HP / 4 Def / 252 Spe
Jolly Nature
- Power Whip
- Thunder Cage
- Spikes / Stealth Rock
- Volt Switch / Knock Off
An actually competent looking mixed set. Thunder Cage damage is negligible, but still threatening due to its chip damage and the Electric Fence boost. Instead, this set aims to utilize Regithorn's decent 97 Atk and a strong 120BP physical move in Power Whip for some surprising damage. Just like most Regithorn sets, the last couple of moveslots are very flexible and can be anything to fit the team.
Offensive Utility 
Regithorn @ Leftovers
Ability: Electric Fence
EVs: 252 Atk / 4 Def / 252 Spe
Jolly Nature
- Power Whip
- Supercell Slam / Wild Charge
- Spikes / Stealth Rock / Knock Off
- Swords Dance
I just found out Ferrothorn retains SD in Gen 8, so here's a fancy offensive utility set. Don't get your undies in a fit, Regithorn still has to utilize two subpar STAB Electric-type moves: Supercell Slam and Wild Charge, the latter absolutely annihilating Regithorn's longevity and the former doing the same thing with a single wrong prediction. That being said, with good speed and decent attack and Power Whip, Regithorn could have the option to turn a game around with a sweep. Your choice of moveslot is once again present, so this could be surprisingly decent under the right circumstances.