Both the speed and the 'when damaged' aspect of Metagon-Z's ability do not have anything to do with either ability, really.
Parents: Metagross + Porygon-Z
Shared Egg Group: Mineral
Offspring Name: Metagon-Z
New Type: Steel/Normal
New Base Stats: 93/118/110/125/93/90 (BST: 629)
New Ability: Unstable Software (when directly damaged, raises Attack, Special Attack and Speed by one stage, but lowers Defense and Special Defense by one stage; Download + Light Metal.)
Notable Moves: (Z-)Conversion, Flash Cannon, Tri-Attack, Psychic, Psyshock, Meteor Mash, Bullet Punch, Return, Double-Edge, Earthquake, Hammer Arm, Zen Headbutt, Thunder Wave, Stealth Rock
Role Identification: For a physical attacker/special attacker fusion to compete with more immediately co-operative fusions, it must be able to set itself apart. The obvious choice is a Z-Conversion sets (special, mixed, and even physical), which becomes stronger and faster with every hit via Unstable Software. Since Z-Conversion boosts all stats, one activation of Unstable Software just returns Metagon-Z's defenses to their respectable bases. Its movepool gives it great versatility: not only in coverage, but also in its post-Conversion type. Support options allow usable if less offensive and glitzy sets. Also, don't forget...
Parents: Metagross + Porygon-Z
Shared Egg Group: Mineral
Offspring Name: Metagon-Z-Mega via Metagonzite (meh-tuh-GON-zeit)
New Type: Steel/Normal
New Base Stats: 93/128/130/135/113/130 (BST: 729)
New Ability: Tough Claws Notable Moves: The same ones. Useful contact moves for Tough Claws include every Notable physical move besides Earthquake, Thunder/Ice Punch, and Pursuit.
Role Identification: This may look like an inferior Z-Conversion Metagon-Z, but Mega Evolving gives important advantages. Not relying on a one-time move gives you more flexibility and vulnerability to Roar/Haze. STAB on two types is quite useful, especially for Bullet Punch. Although this route can't utilize Tough Claws, Nasty Plot is strong alongside 135 SpA, 130 Spe, strong 93/130/113 bulk, solid defensive typing, and a good movepool. Don't forget you can switch it in on a weak attack before it Mega Evolves and exploit Unstabe Software; with its strong bulk, -1 defenses is not catastrophic. Finally, how could you resist a doubly-hyphenated Mega?
Parents: Tapu Bulu + Kommo-o
Shared Egg Group: DNA
Offspring Name: Kommo-Bu
New Type: Fairy/Fighting
New Base Stats: 76 (+3)/134 (+14)/120/93/103 (+3)/100 (+20) (BST: 626)
New Ability: Sheltered Harvest (Grass-type moves become Fairy-type and gain a 50% power boost; Grassy Terrain + Overcoat)
Key Moves: Wood Hammer, Horn Leech, Superpower, Sky Uppercut, Stone Edge, Dragon Dance, Swords Dance, Leech Seed
Role Identification: Fairy/Fighting is an excellent typing (especially offensively) with amazing potential, and Tapu Komo has no shortage of tools to abuse it with. Wood Hammer and Horn Leech, via Sheltered Harvest, give it ridiculously powerful/healing STABs to complement your choice of Fighting STAB. SD, Bulk Up, Autotomize, and Belly Drum give it four strong boosting options to make it even more frightening. Support moves like Leech Seed, Taunt, Roar, and Nature's Madness can use a typing with unique defensive niches. Finally, not only does Sheltered Harvest give a more reliable power boost than Grassy Terrain, but it also doesn't weaken Earthquake/Bulldoze.
coming s00n
More coming!
I have absolutely no idea whatsoever how you got Sheltered Harvest from that combination.
Otherwise they're pretty neat.