Attack on Titanium is the 1st stage of Sweet Irony. Next stage: Wrath of Titanium.
Metal Cyclone is the most durable Metal enemy in the game, so Critical Hitters are a must — and most of them are outranged by Super Metal Hippoe.
- Bring Critters who can outrange Super Metal Hippoe (Major Space Cat is the wiki's pick) so landing crits on him is not a gamble.
- Hard-hitting or guaranteed crits — Jurassic Cat / Catasaurus, Seaside Neneko, Cheerleader Cat — do the actual killing; keep them behind something because most have low range.
- Michelangelo Cat holds the Metals at a distance so the crit stack gets its hits in; Power Backhoe + Li'l Whale adds +1% crit for the whole team.
- The enemy limit is 2, so Knockback-Immune units can pin Super Metal Hippoe and Metal Hippoe at the base while others chip the base down without ever fighting the Cyclone.
- Beat some other Cyclone Stages first — their drops are anti-Metal units that make this fight far easier.
Similarly to other Cyclones, this very slow enemy attacks non-stop and deals extreme damage, but has a tiny range of 65. It takes only 1 damage from non-Critical attacks like all Metal enemies yet has more than triple the health of Sir Metal Seal, requiring a lot of Critical Hits to defeat.
CATASAURUS A Catasaurus/Jurassic Cat Sitter - Able to consistently deal critical hits with proper support. This cat can also be paired with other critical hitters to keep the metal enemies away from your base and deal decent amounts of damage to said enemies. 
MICHELANGELO CAT B Michelangelo Cat - This cat can be used to keep metal enemies at a safe distance and allow you other cats to deal critical hits. 
MAJOR SPACE CAT B Major Space Cat - This cat has a reliable critical chance and long range, allowing him to stay at a safe distance and be stacked to help build a large amount of damage to anything within his range in case of a critical hit. 
CHEERLEADER CAT B Cheerleader Cat - She has a guaranteed and hard-hitting critical hit at high levels, making her great for dealing damage to the Cyclone and Sir Metal Seal, but she is locked behind a fairly difficult stage. 
POWER BACKHOE CAT A Power Backhoe Cat - A below average critter, but if you pair this unit with Li'l Whale Cat you get +1% added to all of your unit's critical chances with their combo. This mostly benefits fast critters like Catasaurus. 
NENEKO B Critters with hard hitting, fast or guaranteed Critical attacks such as Jurassic Cat and Seaside Neneko can be very useful, though do be wary of the low range that most have. Metal Cyclone is Metal — normal hits do 1 damage; only Critical or Toxic damage gets through.
Critical is a chance, not a guarantee — lead with 100%-crit or Toxic units; low-crit ones are slow backups.
CRAZED MONEKO A Reliable Critical hits punch through Metal. 
GLASS CAT A Toxic damage ignores Metal armour. 
CHEERLEADER CAT A Reliable Critical hits punch through Metal. Also fits “Out-range Metal Cyclone.” 
TECOLUGA S Reliable Critical hits punch through Metal. Also fits “Out-range Metal Cyclone.” 
HIGH LORD BABEL S Toxic damage ignores Metal armour. 
BRAINWASHED FISH CAT A Toxic damage ignores Metal armour. 
⚙ More counters worked out from the roster, lower confidence than the picks above; kept for reference
Metal Cyclone reaches 65 range. Units that out-range it can chip safely without taking hits.
GROSS CAT A Range 350 — fires from beyond its 65. 
MASTER URIL A Range 405 — fires from beyond its 65. 
AKU RESEARCHER A Range 400 — fires from beyond its 65. Also fits “Crack the Metal.” 
BACKHOE CAT A Range 350 — fires from beyond its 65. Also fits “Crack the Metal.” 
CAT CLAN HEROES S Range 350 — fires from beyond its 65. Also fits “Crack the Metal.” 
The castle you destroy to clear the stage.