Noob Raid Question?

There are 5 tiers of raids (reflected by the number of faces of the raid egg). You can check the boss list in each tier in the raid page. The boss list will rotate based on either event or something else. Currently it's Gen 1 featured event so most of (all if I'm correct) the raid bosses are from Gen1. It will rotate after Sep 30th. There is no pattern like you described. It's just randomly spawn from it's given tier.

Dratini is from tier 1, which means it's super easy. You can beat it by yourself.

Bosses are usually random, but I've seen some sad, abandoned gyms having the same boss over and over again. Maybe just a coincidence.

It is completely random and the raid bosses change every once in an awhile. https://pokemongo.gamepress.gg/raid-boss-list gamepress keeps a updated list of the only mons you will see during certain rotations of raid bosses. For example, as of this date you will never see a Tyranitar raid boss until niantic rotates them again.

Raid drops are completely random. A Dratini being at a specific at a specific time today doesn't guarantee it will be there again tomorrow. If you want Dratini specifically I'd try to hit every raid you can between now and the 30th as it's likely to be rotated out then.

Dratini is a level 1 raid so it’s the easiest tier for raids, able to be solo’d by most players. You can tell what tier raid will happen by the color of the egg, if it’s pink it will be a tier 1-2, yellow will be tier 3-4, and black/purple will be a tier 5 - legendary raid.

You can do as many raids as you want provided you have raid passes (you get one free pass per day). The higher tier raids require more people, with most tier 3 raids being soloable but tier 4 and above need a group.

Raids are on a timer, once the egg pops up you have something like 45 minutes before it hatches, then another 45 minutes to complete the raid before it’s over, but there’s also no set amount of raids that can occur at any given gym (that I’m aware of).

There’s no guarantee what tier raid or what raid boss will spawn at any particular gym except for EX-Raids, which are invite-only raids you get as a reward for raiding at EX eligible gyms. The gym you did a dratini raid at the other day could have a Rhydon raid there 3 hours later, for example. Or it could have no raids at all, or a Mewtwo raid.

Many people do “raid trains”, where a group of people ride together in one or multiple cars and go from raid to raid to maximize exp and rewards.

Sorry for the wall of text, hope that covered everything lol. Glad you’re enjoying raiding, hopefully you get to do a Mewtwo raid before they’re gone!