This is something I've been interested in awhile. Pirate101 has these, and I figured these could combine a few of the ideas in game already.
Wizard101 Companions would be a PvE only feature that is found in a new tab in the Crown Shop. For a fairly modest crowns price (750-2500c depending on the buff), wizards can buy a helper much like Dyvim or Mellori etc. except instead of only occurring for certain quests or in certain areas, these extra stats would be permanent as long as the companion is equipped. For example, as long as you have "Companion 1" equipped, as long as you are NOT in PvP, you will gain a permanent 10% outgoing healing boost. This is like elixirs, but the boost doesn't wear off.
Some ideas of cheap companions would be: 10% Incoming Healing 7% Outgoing Healing 4% Critical Rating 4% Block Rating
Getting more expensive, stats get better: 15% universal damage 15% universal resist 15% universal accuracy 10% Critical and Block Rating 10% Shadow Pip Chance
Finally, we could have even stronger stat boosts and 'uniques' in the most expensive category:
20% universal accuracy and pierce 20% universal resist and damage Casts a Rebirth for your team every 4 rounds (does not use your blades)-> This is similar to how Darkmoor Malistaire's dragon casts a trap or Daniel in the Simon the Sayer boss casts a trap for you. Casts Blinding Light every 4 rounds 10% chance of absorbing all damage from an incoming damage spell (only occurs once a turn). All spells cast cost one (1) less pip-> (Permanent simplify as long as you have this companion) Ice Mastery Companion-> (Acts like a mastery amulet, but you no longer have to use an amulet to use this mastery. And it allows a person to have two masteries. For example, a myth mastery amulet and a death mastery companion, so you can now cast your own school and myth and death too).
Things like this could be fun. I'd highly suggest that these be kept PvE and No PvP tagged because these could really break the game. However, companions like this could make farming a lot easier, which helps everyone in the long run. Providing an assortment of options lets us choose and collect companions and save up crowns for whichever ones we want. I truly believe that people might be interested in these. I know I wouldn't mind having some extra stats while questing or farming some of the harder dungeons. I'd be willing to pay a small crowns fee for that.