I love nicknaming the pokes on my teams
I almost always have a "Toyota" on my team. It's normally either a bug or a water pokemon. Lately I have used Toyota for Scizor or Kingdra.
My main starter pokemon, like Charizard or Infernape is Chibo. I won't use the nickname Chibo in one of my competitive teams even if there is an Infernape, but I will use it on a favorites team with Charizard, or in a single player team.
Any Metagross I have is Grodus, which I got from Paper Mario 2, since Metagross has a big X on him like Grodus of the X-Nauts.
If I once used a pokemon a while ago I liked then tried it later with a different move set, but then later switched it back to the old moveset I liked, I will add OG to the end of it: Original Gangsta'
Slowbro is Bro **** if it's regular color running my Bro **** set on the Strategy Pokedex, Grimmace if it's shiny, or something else if it's neither.
Butterfree is Chibo on a team where my starter isn't present, otherwise it's Carl
Most of the time I'll nickname Electric pokemon Eric, like Electivire, Manectric, or Jolteon
Registeel is USA, the tag UltimaScout uses in smash, and he's the king of Registeel
Those are the only consistent names I use that I can think of right now.