Well, my favorite is Krookodile, because mine has always been my team's combat backbone.

In terms of Pokemon for waifu potential, Mismagius, followed by Alcremie, Polteageist/Sinistcha, and Mega Banette.
Mismagius is a good companion, but not a great combatant, and I have a killer OC design an artist on here gifted me around the same time I'd caught a Shiny Misdreavus.
Alcremie and the teas can help me enact the feedism/weight gain fetishes I have upon others and are effectively slimes.
Mega Banette is just hot.