Where does jirachi get ice beam and flamethrower from? I can't find them listed on serebii and PS doesn't have them either. If it did get flamethrower, that would definitely be a better choice over fire punch. And like Lugia-sama said, Zen headbutt gets it past toxapex and stuff that resist iron...
I only started competitive battling after drizzle+swift swim got banned, but I did try using a rain team with pelipper in the current meta and it was pretty fun.
For the ccat, I actually did come across something interesting recently that may be worth building a team around-
PO/PS Name?: T-Bolt
Wi-Fi Friend Code?: none
Why do you want to join?: I got into competitive battling again in gen 7 and I don't really have a lot of people to play with. I remember this guild from way back so I figured, why not join?
Number of badges of Serebii Leagues?: zilch
I tried making an OU team but I didn't have any solid ideas. I made a UU volt-turn team with mega beedrill and it was good, but it still has some weaknesses that I'm not sure how to patch. I feel like there's a lot more variety in UU than in OU.