He probably should arrive jokingly to the main protagonist during a Horizon event. He is a newer mercenary at this point of his life, for IMO who is on a new solo undercover job. Investigating Team Horizon acting as a league challenger.
Reactions
Brock: Can't we just do a cook off?
Misty: Love the swimsuit girl. Looks great on you. Unfortunately, I can't swim.
Lt. Surge: A soldier? Would've joined, but my current occupation is stressful enough.
Erika: Tres Bien, Erika! After this, I'm gonna buy some perfume. My brother's wife would love this smell, as I've done to you.
Koga: We're similar, you and I. Men who serve the shadows. But the difference is this; you're honorable, I couldn't careless.
Sabrina: You're a beautiful woman. Yet all roses have thorns. So do I. Let's start this War of the Roses! And after this, I'll take you out to dinner.
Blaine: I know you. We worked on Project Mewtwo before.. Remember? Prof. Nocturne? I guess you wouldn't want to after me and Cyrus left the science field.
Giovanni: I read about you. And know about you.. Prepare to face me.
Lorelei: You remind me of my old protoge at Snowpoint when I was the leader there. Should probably write her back. See if "it" is safe.
Bruno: I look foward to see how a real warrior fights.
Agatha: Oak did mention an old woman that'd give me problems when I started this job.
Lance: No holds barred, right pal?
Falkner: You need to use that Skarmory you caught. Better than using good ol' dad's right?
Bugsy: I remember being a prodigy.. Look how it turned out.
Whitney: Jeez..I'd hit on you if you weren't so whiny..
Morty: Last time I dealt with a loon who dabbled with mythology, I became a criminal. At least you can still change..
Chuck: You're skill in fighting is impeccable. Can it outclass mine?
Jasmine: If Steven gave me problems, what with his obsession with steel, what can you do, miss? Someone as lovely as you could be a bomb in disguise.
Pryce: Celebi saved you before old man..But your sins as the Mask cannot be overlooked.
Clair: Been a while Clair. Lance told you were okay. And lovely as ever. Still angry I dumped you for Cynthia?
Will: I love psychics! And watch how they fail!
Bruno: Overtime?
Koga: As I've said.. Ninjas are more honorable than we mercs.
Karen: Have to admit, among beautiful women, you rank high just because of the Dark-type. I was a Gym Leader once, you know?
Lance: Comes down to this.. How about a drink after this, like old times. Maybe invite Steven, Cynthia, and Wallace. Can I also invite Cyrus if he is, you know, O.K?
He probably wouldn't kill a Lucario, even if he was hired. Code for International Mercenary Organization; jobs are you to choose, not the higher ups. And he has Lucario for one of his mains in his job. And has enough regrets as it is.