1. Who’s your favorite STARTER POKEMON?
I don't have one overall, since I am entirely too indecisive... but for each generation:
Gen I: Charizard
Gen II: Typhlosion and Feraligatr are tied
Gen III: Sceptile (although I prefer Grovyle)
Gen IV: Infernape
Gen V: Samurott
Gen VI: Chesnaught

2. Who’s your favorite LEGENDARY POKEMON?
Raikou overall. Otherwise, we have:
Gen I: Articuno
Gen II: Raikou (redundancy department of redundancy is go)
Gen III: Latios
Gen IV: Darkrai
Gen V: Reshiram
Gen VI: Yveltal

3. Who’s your favorite EEVEELUTION?
Umbreon. Jolteon is a reasonably close second and Leafeon a similarly close third.

4. Who’s your favorite SHINY VERSION of a Pokemon?
Charizard, Pidgeot, Ninetales, Seadra, Umbreon, Absol, Duskull, Rampardos, Victini, Liepard... just off the top of my head, there are too many nice ones. I think it's Ninetales overall, though.

5. Who’s your favorite ALTERNATE FORME?
Overall it's... Giratina's Origin Forme, I guess? Honorable mentions go to Fan Rotom, Deoxys' Speed Forme, Shaymin's Sky Forme, Keldeo's Resolute Form and... I'll toss Dandy trim Furfrou in there for good measure.

Bonus rounds!:
6. Who's your favorite REGIONAL RODENT?
Linoone. I must admit that Rattata and Raticate are classic, though.

7. Who's your favorite PSEUDO-LEGENDARY?
Dragonite. I'm quite partial to Tyranitar, too.

8. Who's your favorite BABY POKEMON?
Uh... Budew? I don't care for the majority of the babies, to be honest...

9. Who's your favorite Pokemon (in general)?
Pidgeot. Until the end of time, I would say.

Look at me making this post so much longer that it needs to be. Like a champ.