Yanmega and Abilities

[Mega Horny]

Any reason in particular my yanmega would gain the ability tinted lens 5 times in a row upon evolution, even though it already had speed boost as a yanma?

[Negrek]

Did you pal park that yanma in from a GBA game?

[Mega Horny]

Yeah.

[Razola]

Tinted Lens is better than Speed Boost anyways.

[TKnHappyNess]

Yanma's got 2 abilities: Speed Boost and Compoundeyes. When it evolves into Yanmega, the latter ability will change into Tinted Lens. If it's got Speed Boost, it'll keep that ability.

[Mega Horny]

Why is it changing for me, then?

[Razola]

Why is it changing for me, then?

Probably because it's a GBA Pokemon.

Tinted Lens is better than Speed Boost anyways.

[Negrek]

Why is it changing for me, then?

GBA pokémon have their abilities randomized when they evolve in D/P, due to the way that dual abilities are coded. Therefore, a yanma with speed boost caught in D/P will always have speed boost, but a pal parked yanma only has a 50% chance of ending up with the speed boost ability upon evolution. Once it is 'Parked, the evolution ability is set, so evolving and resetting in an attempt to get speed boost won't work.

It is unknown whether clones will all gain the same ability upon evolution in D/P.

[Mega Horny]

I'm raising mine with the power anklet which reduces speed evs, increases Sp atk though. What makes it better? Steel type foes?

[Razola]

Power Anklet reduces speed STAT, not EVs. You have it completely backwards: the Special Attack EVs are boosted, but speed is stat is reduced. Once you take the the "Power" items off (as well as Macho Bracer), your speed stat returns to normal.

Yanmega is fast enough as is it, and boasts a high special. Make it Timid and then your opponent will take considerable damage no matter what move you use. If Yanmega learned Baton Pass, I'd definitely consider Speed Boost, but it doesn't.