Which Aniimo have Tunnel?
6 of the 86, and 3 of those can be caught in the wild rather than raised.
What it does. Tunnels underground to become immune to all ranged attacks by continuously consuming stamina. Pound skills can launch the Aniimo into the air.
Tunnel is a Mobility ability. Those are recorded apart from the three Pathfinding abilities — Fly, Swim and Climb — that clear an obstacle outright. What the separation means in play is not stated anywhere, and this page does not guess: it tells you who has it, which of them you can go and catch today, and where.
Catchable now
Raised, not found
These have no habitat in the dex, which means evolving one is the route. Follow the chain back on each page.
No grade, and no note about what it opens
Traversal abilities come graded — Fly Lv.1 through Lv.3 — and this one does not. The dex gives Tunnel a name and a sentence and stops, the same sentence for all 6 Aniimo that have it, with nothing to separate them.
That means the choice between them is not a choice about the ability at all. It is a choice about the creature: its element, the fights it is good in, and how long it takes to get. So the rest of this page is about that, and there is no ranking here because the game does not publish one.
Where to go looking
The 3 catchable Aniimo on this page are spread across 4 regions. Berylline Causeway has the most at 2, then Zephyrus Landbridge at 2 and Beast Fang Ridge at 1. A creature can be listed in more than one region, so those numbers count sightings rather than creatures.
2 of those regions — Beast Fang Ridge and Nimbus Fields — hold exactly one, which is the more useful fact of the two. A region with one entry is not a place to go hunting in general; it is the only place that particular Aniimo turns up at all, so if that is the one you want, that is where you go.
Habitats are the game's own, not ours. Where a page here shows a region the game does not put that creature in, it is a mistake and not a tip — what we will and will not print.
Does it come attached to an element?
Worth checking before you build a party around one answer, because an ability you can only get on a rock Aniimo is an ability that costs you a slot in every fight it is bad in. Here it leans rock — 5 of 6 — with the rest across ice (1).
That is a distribution, not a rule. The dex gives no reason why the two travel together and we are not going to invent one; what it is good for is narrowing a search, and knowing before you start that the Aniimo which solves your map problem may not be the one you wanted in your team.
Which one should you get?
Not answerable yet, and not answerable anywhere else either. Every Aniimo on this page has the same Tunnel ability, described in the same words, so the question is which is fastest to obtain. That needs a measured drop rate, which does not exist for this game today, here included.
That is what we are measuring now. How it works. Nothing here is estimated.