i'm doing this for angie but i might need this one day myself. probably not.
WARNING: i probably might have put some spoilers in here too please don't hate me

Hey look there's a 'list of companions' page on the doctor who wiki that will make this so much easier.

The ninth doctor obviously had Rose, and Captain Jack Harkness, and I believe Mickey was sort of a companion too. (And Jackie. Like once.) Then there's Adam Mitchell who I don't really remember but he was in the episode Dalek idk. I think that's it for the ninth doctor?? I could go through all the thirtheen episodes but come on I'm lazy.

The tenth doctor. Now it's gonna get complicated.
There was this really wonderful episode where he had Rose, Martha, Donna, Jack, Jackie, Mickey, Sarah Jane Smith, and Harriet Jones for a while (but this was only one episode so idk if they all count as companion?? i like to believe so). I like to think Cassandra was a companion because she was Rose once but I'm the only one so let's move on. K9! I ALMOST FORGOT ABOUT K9 IN SCHOOL REUNION YOU CAN HIT ME IF YOU WANT. Mickey was a companion for a few episodes in season 2 idk. Maybe I should mention that I don't like lists so this is turning into more of a little story?? I'm sorry if I dissapoint you.
So then there's Martha who I obviously don't really like. I see Sally Sparrow as a sort of companion even though she only met the doctor in person for like five seconds. I probably should be telling you who are actual companions instead of saying what I think. Sorry.
Astrid Peth was an actual companion who I only remember from Voyage of the Damned (christmas special) but apparantly she was in Journey's End too.
Then Donna. Donna's awesome. Martha and Donna were companions together in a few episodes and yeah. JENNY WILL ALWAYS BE A COMPANION TO ME BUT THIS IS MAKING ME SAD BECAUSE THE DOCTOR DOESN'T KNOW SHE'S STILL ALIVE. Then River in Silence in the Library/Forest of the Dead. River's awesome, too. In Midnight there was no companion, Donna kind of was away while the doctor went on an adventure so I guess everyone on the bus was a companion, sort of. SO MANY PEOPLE IN JOURNEY'S END.
In 2008's christmas special (The Next Doctor) Jackson and Rosita were companions. Dunno if you knew this but in 2009 there were no episodes. Just specials. In Planet of the Dead Chritina was the companion, in The Waters of Mars Adelaide, and in The End of Time Wilfred.

Literally the first face eleven saw was Amelia Pond's idk you probably already knew this. FISH FINGERS WITH CUSTARD. River's a companion too (she literally is in random episodes) and of course Rory. I WILL ALWAYS BELIEVE VINCENT VAN GOGH WAS A COMPANION YEP. Also Craig. Craig is a companion too and no one will ever tell me otherwise. HE'S THE ONLY ONE EVER WHO STOPPED HIMSELF FROM-- oops spoilers. I'm sorry. I love the episodes where Amy, Rory and River were all companions. 2010's christmas special (A Christmas Carol) had Amy and Rory but 'featured' Kazran and Abigail so idk. Have you ever seen an episode with the Silence? They freak me out. The Curse of the Black Spot featured Henry Avery. THE TARDIS BASICALLY WAS SOME KIND OF COMPANION IN THE DOCTOR'S WIFE OKAY. I've been using caps a lot. I talk a lot when I'm nervous. I'm nervous cause there's pe tomorrow. (I wish it was pie not pe.) In The Almost People the eleventh doctor's ganger was sort of a companion too. A Good Man Goes To War just features a lot of people I've been typing a lot and I'm sure you're really bored right now so yeah. THERE'S A MINI EPISODE WITH ALBERT EINSTEIN AND I DIDN'T KNOW?!?
I really like 2011's christmas special. And then idk in season 7 part 2 it's Clara but I haven't gotten to the episodes after The Angels take Manhattan yet so I'm gonna have to stop here.