As you've already had lots of good advice, there's not much point my sticking my 2 cents in, but I will anyway, and then I'm broke...
As far as the individual betta temperament goes, if you have a delta/half moon strain, in my admittedly limited experience, you are far more likely to wind up with a betta better suited to life with other fish.
Crowntails tend to be crabby and plakats may prove not only more aggressive but, as faster swimmers unhindered by longer fins, more likely to catch up with any fish they may decide to chase.
I have a fish sold as a half moon who probably would be, going by the number of folds in his sweeping drapery, if I'd ever seen him flare.
He lives in a tank with pygmy cats, a male guppy/Endler cross, WCM, and a young female Bristlenose who I'd actually planned to move out some time ago into her destined home.
No problem.
I have another bought-as-half-moon who would have been if his top ray wasn't bent the wrong way, who lives with a guppy/Endler cross and who is intended to move into a tank with Harlequin Rasboras and eventually pygmy cats, once everybody's healthy.
I don't expect any problem, and would be very surprised if any arose.
Neither one can outswim the typical fish, and they know it, so don't bother trying, at least not for more than an inch or two, and not often.
I have two crowntails who, if they ever share a tank with anybody, will have carefully selected roomies, probably armoured, just in case.
Although the older one's mellowing and no longer flares, as he did initially, at Mum or his own reflection.
(This may have been a fear reaction, as he couldn't swim when I first got him, and was terrified of me and had to wriggle away on his tummy when I cleaned his Q tank every day.
So when he could swim and stand his ground, and got into his own 10 gallon tank, he flared, because he finally had the ability to fight or flee and therefore face down his terror.)
The trick is to move the betta in after the other fish have settled in, and to have a well-planted tank with room for avoidance and places for privacy.
This sets the psychological stage for sharing, because the other fish were there first, and are part of the scenery.
Although it's always a good idea to have a spare tank set up, if possible, just in case, and to keep a watch for signs of any potential problem developing.
If you're worried about a problem developing due to the behaviour of your individual fish, you're probably better off not trying it, as you'll know your particular fish's tendencies better than anyone else could.
And you can't undo an injury or maiming.
(Not shop workers, and stuff.)
