I'm glad you're enjoying the project!
The event tickets are all obtainable, although some are easier to get than others:
- Old Sea Map: This will be given to you at the Cove Lily Motel after registering all non-mythical Kanto Pokémon in your Pokédex.
- Mystic Ticket: This will be given to you at the Weather Institute after completing the roamer quest (capturing Latias/Latios, Articuno, Zapdos, Moltres, Raikou, Entei, and Suicune.) The roamer researcher at the Institute will mark the active roamer as "seen" in your Pokédex to help you track it down easier.
- Eon Ticket: After defeating the Elite Four, the delivery man will be waiting on the second floor of the Pokémon Centers with this item.
- Aurora Ticket: This will be given to you at the Mossdeep Space Center after registering all non-mythical Hoenn Pokémon in your Pokédex.
For the other legendaries/mythicals:
- Mewtwo: After defeating the Elite Four, Mewtwo will be on Mirage Island. (The island will be visible as long as Mewtwo is active. Once it's captured, the island will return to its normal mechanics, so make sure to grab the Liechi Berry while you're there!)
- Celebi: An Ageto Celebi will be given to you at the Cove Lily Motel after registering all non-mythical Johto Pokémon in your Pokédex.
- Jirachi: A Wishmaker Jirachi will be given to you at the Cove Lily Motel after registering all non-mythical Hoenn Pokémon in your Pokédex.
For the rest of the Pokémon, you can check the encounter data
here. It should be fairly easy to figure out if you search the page for the species you're looking for. Anything you can't find there will be a stationary encounter, trade, or a gift.
As for your requests, the first two were actually features I had started planning out before deciding that they had a little too much of a "non-Game Freak" feel to me for them to fit in. The EV cap is a pretty good idea that I haven't thought of. I think it should probably be fairly easy to implement, so I'll look into it. In regards the the HM item, I specifically did not create any new items to maintain save compatibility with Emerald. You might have noticed the the Charm effects just change probabilities without actually granting you an item. I might look into allowing HMs to be used as long as you have a species in your party that has the ability to learn each HM, but I'm not sure what the complexity for that will be.
I very much appreciate the feedback, though, and I hope you're having fun with the game!