It takes up three monster spaces, meaning it is so large, it is the only monster the player can have out at one time. (dragon-quest.org)
Slimes are typically the weakest enemies in every game, having no special abilities and being easily disposed of, and likely the first monster the player ever encounters in a battle. (dragon-quest.org)
Tsujimoto didn't share any details on what kinds of monsters players can expect or give a time frame for when they will arrive, but he did confirm that the monsters will come as free post-launch updates. (gamespot.com)