What colour variants does Irisalis have?

The pink and purple look is the normal one. Every other colour on this list is a sparkling form. The blue cosmic version is the most elaborate of them, with glowing wings and celestial effects. The others are dark red, gold, and an orange and red fire theme.

A sparkling Irisalis also gets a unique background on its information tab. That background belongs to the season-exclusive legendary sparkling appearance, so you can tell one apart from a standard catch without looking at the creature itself.

How to get a sparkling Irisalis

You don't have to hope for a lucky roll. You craft Iris Petals into the Irisalis Aniipod from the event menu, and that pod summons and captures Irisalis. Spend more petals and you can make Wind Chaser's Departure, which takes 49 Iris Petals. Anything caught with it is guaranteed to come out sparkling, with perfect innate potential, and catches with these crafted pods always succeed.

Petals are also currency in the Legendary Journey event shop. Some shop items, Glimmering Driftshadow among them, stay locked until you have crafted the legendary pod, so don't spend petals in the shop first. The linked article covers the costs and the order to spend in.

Customization is not the same as a variant

The event also sells cosmetic options. If you pay with the free Glimmer currency, you only get the first few, such as colour, wings and headwear. Those cosmetics are separate from the sparkling forms. Part of the Irisalis Prismana transmog can be earned without spending real money in the Forest of the Butterfly Dreams event.

Not settled: Nothing here says which sparkling colour you get from a guaranteed sparkling catch, or whether you can pick one.