Oh I got another question about berries, since a number of berries only have a use in pokeblock/poffin, and since we don't have contests in this game (at least not yet I dunno what you intend to do) what good are berries like Spelon, Bluk, Razz, Watmel, or others like them that the berrydex says are used mainly in pokeblock or for making berry powder? Might it be possible to find some other use for them in the next version, or whatever future release you might think of doing down the road? An obvious choice would to be to sell them for extra cash but I would think having more variety of things to do with berries might be better if at all possible.
Like perhaps specialized pokemon food which can help make a pokemon friendlier, or add some other form of benefits. I hear Essentials 14 features some mechanics seen in some of the more recent games, like I heard that there was a feature to emulate "move experiance" like which is seen in Pokemon Mystery Dungeon: Gates to Infinity. This would be an amazing little mechanic to use to add a world of new strategies in the colloseum since it would allow for a wide variety of choice in move sets beyond what we have right now. If using those berries to work move experiance could be done that'd be worth implimenting.
Besides that if anything else a big thing to work on IMO is some grammar issues as well as revised diologue for many of the characters. Especially since many repeat their end battle message if you talk to an NPC after battle, it seems kinda weird to make them like a broken record almost. And definately see about giving the opening diologue to trainers who you re-battle a overhaul too as everyone saying "Rematch?" robs a lot of immersion I think.
As for the trainers you fight in the Arena alongside the rival, I could see story events occuring with each of them, might it be possible to have more plot events?