I've never done one of his quests before since I wasn't interested enough in any of the pets' Galactic looks way back (I was one of those really old accounts that got cleared), but I'm planning to get one now. Since I never attempted any of Iltallo's quests, idk how this works. I read that at most he'll ask for 8 crystals at once and I'm not even sure about that. What I'd like to know is that all 8 are a different colored crystal or will he ask 2 of the same crystal for example- thanks a bunch in advance!

He asks for one of each crystal, I think

and crystals are so cheap there's no reason not to buy from user shops if you are lacking any.