@Background Pony Number 17  
Season 1 already established that Spike had trouble managing animals due to his unfamiliarity with them; as shown with how Angel Bunny was so antagonistic to him in Dragonshy. The near-entirety of Season 3 should have been rewritten because most of what was in it regarding Spike went in complete conflict with what we saw and knew of him back in the previous two seasons. It was in Seasons 3 and 4 that had Spike going from a reliable sidekick character that had the potential to become an active participating member of the Mane Six, to instead being written as a Butt Monkey and a chew toy for the writers in-terms of how often Spike got abused by others and even by his own friends.
 
For instance it was already both shown and implied that Spike was a cook due to what we saw in Owl’s Well that Ends Well and in Dragon Quest, so the scene where he was making a mess of Applejacks’ kitchen in Spike At Your Service doesn’t work on a narrative level.  
Then there is the events of Just For Sidekicks. No. Just, no. What was even the point of keeping Spike in Ponyville while the others went up to the Crystal Empire when the six of them don’t really have much of a connection with the Imperial City unlike Spike who was the one to actually deliver the Crystal Heart that defeated King Sombra. As was shown in later Seasons, Spike is a national hero there and would have plenty of stories you could write involving him there with the others.
 
Hell, we could maybe even create an entirely new episode or arc where Spike runs into some Dragons from the Migration that do not subscribe entirely to the “Rawr, Rawr, Fear Me!” philosophy that other Dragons like Garble had (probably Fizzle: the Albino Teen Dragon due to how un-antagonistic he was towards Spike in the group in that episode), and FINALLY give us some damn Dragon Lore much earlier and see Spike and his new Dragon friends bonding through the incorporation of their talents and skills while also defining their own version of Dragon Philosophy and what it means for them.

@Background Pony #3DB6  
I found your comment funny.

Twilight:  
(Mumbling in her sleep)  
“Oh, that’s right, Flash…Lower…Lower~…”<3
 
(Wakes up and realizes it was Peewee cuddling her)
 
Twilight:  
“What the–!? PEEWEE?? ….I didn’t say stop…”
 
Peewee:  
“…..??“O_o

Twilight Sparkle got…books.
 
She also got a boyfriend, but due to him being non-canon, she was not allowed to keep him.

@Background Pony Number 17  
Spike’s displayed problem wasn’t that he wasn’t able to take care of a pet, but that he wasn’t giving the job the amount of respect it deserved (taking on more pets just because of more reward, trying to shove them off on others, and focusing more on the cake).
 
It’s not against the message of Just For Sidekicks that Spike was able to take care of a pet where:
 
1: Spike had a much bigger investment in the pet (and thus he would take its care more seriously).  
2: There’s only one of them.  
3: He doesn’t have to deal with anything that has a temperament as bad as Angel or Opal (let alone both at the same time).  
4: He has Twilight (and probably Fluttershy) to help out or give advice when he needs it.

@Background Pony Number 17  
But I’m not sure it’s exactly him not being mature, just a lack of information. Even if he is young, he has shown himself to be rather responsible, and there was times he took care of animals before that, specifically ‘Dragonshy’ where he was responsible for most of Fluttershy’s duties at her place, and it didn’t seem to go catastrophically wrong.
 
The difference there is that he was offscreen, where Spike seems to do his best work most of the time. When he’s onscreen, especially when it’s a ‘Spike’ episode, that’s when he tends to usually be nerfed and bungling, which can be understandable given it’s supposed to make the episode more interesting than what is probably a normal day as a library/research assistant, but it also tends to be the source of inconsistency that causes a lot of Spike-centric episodes to be less than well recieved.
 
Honestly, the best kind of Spike episode would probably just be a short few minute tidbit in an episode like ‘Slice of Life’, no big emotional issue, no big-bad end-times event, just his normal life, since we now know he has one outside of the Girls after the first episode of this season, and his normal duties with his normal interactions with normal citizens

@Background Pony #D85C  
Honest mistake or not, the point the animators were making was that Spike wasn’t mature enough to be a pet caretaker just yet. That was the whole premise behind “Just for Sidekicks”. Like a lot of Spike episodes, the conflict started with Spike overestimating himself, and it was resolved by him having to learn his limitations the hard way.

@Background Pony Number 17  
First off, a lot of animal stuff seems to be different in Equesrtria. Secondly, he does look sorry, and given not even Fluttershy knew much about them, it could be an honest mistake about Phoenixes

@Background Pony #CB4C  

 
Umm, look closer at the pics. Spike was trying to feed Peewee ice cream. Probably not a healthy diet for a baby phoenix. The pics were shown at the beginning of the episode specifically to point out that Spike ISN’T capable of taking care of a pet.

@MrXemnas1992  
Certainly would have made a better Spike episode than the one’s we’ve gotten recently.

@Blood Brandy  
^ Actually, that’s right on the nose.
 
I don’t mind that Spike returned Peewee to his parents, but what I do mind is that they made it look like the chick would become a new supporting character (or whatever category the pets are in)…only to unceremoniously “put him on a bus” a season later.

@mckinnley  
I think some folks problem is it all happened without us seeing it. We never saw Spike having fun with Peewee. He’s just seen being hatched and named, then the only interaction we see between him and Spike is in a few photos so he could be written out off screen. It’s kinda like if we went through all the stuff of ‘Owls Well That Ends Well’, then never saw Owlowicious again at all, ever, except in a couple of pictures where Twilight has to send him away.
 
It might have been better to either give him an episode, or at least have the phoenix appear in the background with Spike in a couple, before getting rid of him, or just give him hack to his parents in Dragon Quest instead of taking him back to Ponyville at all. Heck, it might have been better to send him to Celestia, who also has a pet phoenix, with some sort of reason that young phoenixes need special care or had something to learn from Philomena. To go through the rouble of binging him in, naming him only to get rid of him off screen just basically says they had no solid idea what to do with him, which honestly, seems to go a lot for Spike stuff.

@GoldenSun  

 
The pics show that Spike is capable of taking care of a pet, but the episode completely contradicts it, lol.

@FaustXXXVII  
Get out.

@GoldenSun
 
Yeah, Twilight was totally aware that the presence of the Phoenix was affecting the behaviour of his slave possitively so she had to make him give it away.

@SilverSnapple
 
I believe that makes a whole lot more sense

@Yoga is boring  

 
I agree.
 
@GoldenSun
 
Now i see. Thanks.

@GoldenSun  
That looks like it would have been a better episode than what we actually got with that lackluster pet episode.

@raw19  
Just for sidekicks.
 

@mckinnley  

 
Where and when was this? Cuz i literally blinked and missed something, then.

I downvoted it before realizing it is not cheap shot at DQ but T4S reference.

I don’t get it. They had a follow-up showing him give it up and everything. People seem to be talking about this as if the bird was just suddenly gone

some sort of episode where he had to give up peewee would be nice.

@MrXemnas1992  
I can completely understand.  
It’s also not really funny. You just stated  
“Spike had a pet, but now he doesn’t”  
 
The real joke is in the description.

@Background Pony #7DD3  
Well, not all of us can draw, y’know…
 
stares at drawing tablet gathering dust and sobs