A couple of ideas.
 

Referral System
For every new member a user refers to the site they are rewarded with items, cash, or rarer pets.

Ability to put pets or items on "Sale" or "Clearance"
Brought up by schepers12 in this thread. I could see it working with a radio buttons for Price Status (Regular, Sale, Clearance) and then a box for each price point (sorry, retail background there).

Integrated News/Blog System for Admin Team
A way to make updating the main page easier, I have found a php script (CuteNews) but it isn't the easiest. If you'd like there is a simple tutorial posted on the girlswhogeek website.

Different Currency Types
Two or more currencies, one that everyone can earn by clicking on pets and playing games, and one where you either have to meet conditions (keep all pets happy, fed, etc... for x days in a row) or pay with IRL money to receive.

I can't think of any others right now, but will post if I can. Would you like mockups as well?

User Status/Mood
Display a status with what a user is currently working on, plus their current mood. (Seen on Flight Rising, GPX+)

Well I thought there was a Mys v1.4.0 idea thread in dev staff forum? Why not post in that thread?

Anyway, the referral and multiple currency seem to be easy, the other two may require a bit of work so I aint sure if they will be included in Mys v1.4.0. These are good ideas though, some may come out as official features while others may be released as Addons/Mods for Mys v1.4.x.

I forgot... :3 I'll merge this thread with that then. ;3

And yeah, I figured that some of these ideas would work. We'll just have to learn how to do them.

Thats true, also its necessary to make sure that these features are easily customizable. Tbh this is the hard part, as users are so different and they want to do different things with the features we provide.

One more.

Treasure Chests
Open to find an assortment of random items. Vary chests by specific types (currency, food, clothes, etc...).

umm this is an interesting idea, if you have an exploration system it can work pretty well. Since exploration system wont be available in recent future, I will have to find another possible way to integrate this.

Brute-force attack countermeasures and CSRF prevention would be awesome. ouo For the brute force, it could be something like if a user has 5 failed logins, their account would be locked for a certain period of time (The number of login attempts and the blocked attacker's IP being stored in the database?). For the CSRF, perhaps something like the chosen answer here? c:

Thats a great idea, and actually I do plan to block brute-force attack in Mys v1.4.0, or maybe as early as Mys v1.3.4 if possible.

As it's O-Dark Hundred here and my Insomnia has returned in force... How about a few new ideas?

Nests/Litters for when there is breeding done. You'd get a place to upload an image to represent the background where eggs/newborns would be shown on top of.

Limited Adoptable Space but you can expand by paying site currency/secondary currency (I've only seen it on Flight Rising).

For PKMN Sites A six slot main team limit. Then have the standard 20 PC Boxes, but you can purchase more if needed.

An upgrade to the old Advertising System as these sites really are not feasible to run for free when it comes to hosting and support. Able to be linked with Google Ads, etc...

Adoptable Stats stuff like age, birth/hatch date, if clans are implemented which clan is it from (using images/text), level (for quests and battles), STR, DEX, INT, WIS, CHA, CON (if you need explanation on these please feel free to ask, maybe awake but I'm too tired to explain... could also change depending on site theme, I just used D&D basics), breeding status, etc...

And that's all I've got for right now...
Signing off at 0425 EDST...