Companion creature MMORPG's?

I like games like pokemon and such. Also like runescape, with the quests and many things to do.
Recently I've been playing a game on the iPhone called "Battle Camp" where you get monster companions to help you advance further through the game, meet people, and accomplish quests.
What I'm asking is, are there any multiplayer rpg's like this? Like a pokemon game, but it doesn't end after you beat a boss, and there are other people in it.
I love the whole companion creature idea, and if anyone knows an mmorpg similar to what I'm asking for, it would be much appreciated.
(like getting stronger and evolving your monsters)

There's quite a few Pokemon MMOs. The best out of all of them by far is PCO (Pokemon Cyrus Online). At the moment, they just wiped the game to make it better and create a newer area. Basically, it is the same thing as any Pokemon game. It has 8 badges, you train on wild Pokemon, there are a few in game quests (although they are really small and don't make that much of a difference). I do have to mention a couple things. This game is pretty challenging. You need to grind on wild Pokemon to level up. At the moment, there's only 4 available GYMs to beat (Like i said, the game was wiped and they are releasing newer things as time progresses. The rest of the GYMs will be out soon). You can battle other players, you can join crews, you can trade, hunt for rares and sell them.

Unlike other MMOs, this games graphics are a lot better (Uses Gen 5 tilesets for maps) and its really simple to use. If you have questions, ask in global chat.

I've played a lot of Pokemon MMOs and basically, they are all old. They have fire red/ leaf green graphics. Not a lot of Pokemon. You have to donate money to get the good Pokemon. The chat systems are really confusing and you never know who youre talking to. The storyline and maps are the exact same as the Fire Red/ leaf green games.

In PCO, they have brand new tiles, donations aren't necessary, it has a lot of Pokemon to choose from, the chat is so simple to use, and the best part, all the maps are customized, it is its own brand new region, all the GYM leaders are customized and thought out well. The game has tricky routes and annoying dead end paths. But thats what makes it enjoyable.

I've played the game for 4 years now, and I was one of the staff for a little while. (I made the maps. Now there's some noob named Buster that maps and he sucks so bad. Lol he thinks hes good.) Erm.anyway. Yeah its a lot of fun, and one of the best Pokemon MMOs out there.