ummm.. humm... I dunno. I guess.. Eevee maybe. Or.. Satoshi/Ash? and talk about Pokémon. Haha. and stuff. you know. What friends talk about.. which is mostly random crap.
I'd have lunch with Ash, build up his trust and friendship in me and then *bam* hit him with the big question. Who do you like better, Ash, Misty or May?
Harley. Yes. If a pokemon, Espeon. :<
(And maybe Max too...)
What I would talk about? Prolly about biology, psychology or religion stuff 'coz I'm boring like that. 8D But I'm generally not the one to start conversations. XD;
Combusken......... Oh, right, this is who you'd like to have lunch with, not who you'd like to have for lunch. I'd probably like to have lunch with Prof. Birch, as I'm desparate to find out about Pokemon anatomy, and we'd have plenty of time to talk it over.
Sabrina. Take her out to lunch and 'chat'.
Now, if the lunch was more of a 'date', I'd go with Lance. If there wasn't a chance in Hell of him being able to come, then I'd have Morty/Eusuine come instead.