Oran-Rief Ooze 

Creature — Ooze
When this creature enters, put a +1/+1 counter on target creature you control.
Whenever this creature attacks, put a +1/+1 counter on each attacking creature with a +1/+1 counter on it.
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Cards that do something similar expected a card that isn't here?
Reports become test cases the matcher is graded against before an update ships. Delvefall isn't a chatbot guessing, it compares the printed rules text of every card with plain math, and examples like yours decide which differences should count.
Fangren Firstborn 91%
$2.46#15366
"Whenever this creature attacks, put a +1/+1 counter on each attacking creature."
Rubblebelt Raiders 86%
$0.13#17880
"Whenever this creature attacks, put a +1/+1 counter on it for each attacking creature you control."
Gideon, the Oathsworn 85%
#17669
"Whenever you attack with two or more non-this card creatures, put a +1/+1 counter on each of those creatures."
Titans' Vanguard 85%
$0.16#8020
"When you cast this spell and whenever this creature attacks, put a +1/+1 counter on each colorless creature you control."
Kalonian Hydra 83%
$5.82#1096
"Whenever this creature attacks, double the number of +1/+1 counters on each creature you control."
Makeshift Battalion 83%
$0.13#22067
"Whenever this creature and at least two other creatures attack, put a +1/+1 counter on this creature."
Sun-Blessed Guardian // Furnace-Blessed Conqueror 83%
$0.09#26825
"Whenever this creature attacks, create a tapped and attacking token that's a copy of it. Put a +1/+1 counter on that token for each +1/+1 counter on this creature. Sacrifice that token at the beginning of the next end step."
Bounding Felidar 82%
$0.18#10971
"Whenever this creature attacks while saddled, put a +1/+1 counter on each other creature you control. You gain 1 life for each of those creatures."
Charging Hooligan 81%
$0.14#27011
"Whenever this creature attacks, it gets +1/+0 until end of turn for each attacking creature. If a Rat is attacking, this creature gains trample until end of turn."
Grotag Bug-Catcher 81%
$0.12#24173
"Whenever this creature attacks, it gets +1/+0 until end of turn for each creature in your party."
Big Mother Mouser 81%
$2.07#6054
"Whenever this creature attacks, double the number of +1/+1 counters on it."
+1 more matching line
Vrestin, Menoptra Leader 81%
$0.28#13296
"Whenever you attack with one or more Insects, put a +1/+1 counter on each of them."
Andúril, Narsil Reforged 80%
$16.59#2688
"Whenever equipped creature attacks, put a +1/+1 counter on each creature you control. If you have the city's blessing, put two +1/+1 counters on each creature you control instead."
Rampaging Classmate 80%
$0.27#25040
"Whenever this creature attacks, it gets +1/+0 until end of turn for each other attacking creature."
Virtuous Variant 100%
$0.20#30209
"When this creature enters, put a +1/+1 counter on target creature you control."
Pridemalkin 100%
$0.36#4349
"When this creature enters, put a +1/+1 counter on target creature you control."
Jukai Preserver 100%
$0.10#23075
"When this creature enters, put a +1/+1 counter on target creature you control."
Kujar Seedsculptor 100%
$0.30#21353
"When this creature enters, put a +1/+1 counter on target creature you control."
Rayblade Trooper 100%
$0.18#15208
"When this creature enters, put a +1/+1 counter on target creature you control."