Parents: Aggron / Tyranitar
Shared Egg Group: Monster
Offspring name: Aggrotar
New type: Steel / Dark
New base stats: 95 / 132 / 155 / 87 / 90 / 65 (BST: 624)
New ability and desc: Sturdy Sands (Sand Stream + Sturdy): Summons Sandstorm and always lives a hit from full-health in sandstorm.
Notable moves: Autotomize, Crunch, DDance, Dragon Tail, Earthquake, Elemental Punches, Fire Blast, Flamethrower, Foul Play, Head Smash, Heavy Slam, Hone Claws, Iron Head, Low Kick, Rock Polish, Rock Slide, Stealth Rock, Stone Edge, Superpower, Taunt
Role identification: An interesting defensive mon with 2 immunities and many resistances. 95 / 155 / 90 is great bulk and could be used well as a defensive lead thanks to Taunt and Stealth Rock. With a massive 132 attack it can also be a physically offensive tank, but if speed is what you want, Rock Polish and DDance are both great options. Nice offensive and defensive Pokemon.
Parents: Aggron / Tyranitar
Shared Egg Group: Monster
Offspring name: [MEGA] Aggrotar (Aggronite)
New type: Steel / Dark
New base stats: 95 / 162 / 205 / 87 / 110 / 65 (BST: 724)
New ability and desc: (Filter)
Notable moves: Autotomize, Crunch, DDance, Dragon Tail, Earthquake, Elemental Punches, Fire Blast, Flamethrower, Foul Play, Head Smash, Heavy Slam, Hone Claws, Iron Head, Low Kick, Rock Polish, Rock Slide, Stealth Rock, Stone Edge, Superpower, Taunt
Role identification: A more defensive Pokemon, 205 / 110 defenses are a great improvement. Probably defensive wall being the best way to go thanks to Filter, it can be an interesting choice for a team due to its interesting typing.
Parents: Aggron / Tyranitar
Shared Egg Group: Monster
Offspring name: [MEGA] Aggrotar (Tyranitarite)
New type: Steel / Dark
New base stats: 95 / 162 / 195 / 87 / 110 / 75 (BST: 624)
New ability and desc: (Sand Stream)
Notable moves: Autotomize, Crunch, DDance, Dragon Tail, Earthquake, Elemental Punches, Fire Blast, Flamethrower, Foul Play, Head Smash, Heavy Slam, Hone Claws, Iron Head, Low Kick, Rock Polish, Rock Slide, Stealth Rock, Stone Edge, Superpower, Taunt
Role identification: A slightly more offensive Mega, the best reason to use this over Aggronite is because of the speed increase, making DDance / Rock Polish much better options, and thus this Mega is more of a set-up sweeper.
Credit to SpartanMalice again for ideas! And I believe this is my last Pokemon for this round. :]