Gengar is much better imo for the following reasons:
- Has great niche in Perish Song + Shadow Tag
- Decent defenses in 60/80/95
- Great offensive typing
Here's why people might choose Alakazam-Mega over Gengar-Mega
- Better offenses and speed
- Offers niche in the form of Trace
- Great pre-mega ability in Magic Guard
- 10 points better Special Defense
- Access to utility moves like Encore and Substitute
Gengar-Mega is much better in OR/AS doubles as
Gengar-Mega @ Gengarite
Ability: Cursed Body
Timid Nature
EVs: 252 Spe/52 HP/20 Def/172 SpA/12 SpD
IVs: 0 Atk
- Shadow Ball
- Sludge Bomb
- Will-O-Wisp/Disable
- Protect
Description: Blatantly stolen from smogon. Nice support, and cripples many sweepers with Will-O-Wisp. However, this is still in Talonflame's reign of terror, so beware him. (Basically Disable's sole purpose)
That's about it. However please consider this:
Better format your Pokemon sets. Your formatting looks something like
Gengar (M) @ Gengarite
Trait: Levitate
EVs: 252 HP / 4 SAtk / 252 Spd
Timid Nature (+Spd, -Atk)
Perish Song
Substitute
Protect
Shadow Ball
When it should look like
Gengar (M) @ Gengarite
Ability: Levitate-->Shadow Tag
EVs: 252 HP/4 SpA/252 SpD
Timid Nature
- Perish Song
- Substitute
- Protect
- Shadow Ball
And then add a description for viewers to better understand the Pokemon's role and purpose.
Also, please use the AMERICAN version of things, not the British version. Examples include: Trait/Ability, Boil Over/Scald, Grade/Year, Color/Colour, etc.